Hello all, this is my first year with a pool and I am so glad that I found TFP! It has taught me so much and made caring for my pool so much easier (and cheaper) than all the horror stories that I heard before purchasing our house with the pool.
I have done a ton of reading on these forms and have bounced between numerous pinned forms for the information that I needed. After getting a grasp on things, I decided to compile all the information into one place and break it down into sections (Chlorine, CYA, pH, TA, CH) and list what increases and decreases each of these parameters so one can focus in on an issue and know how to address it and what the effects will be.
I do not bring any new information to the table, I just complied the information from:
Definitions and Abbreviations
ABCs of Pool Water Chemistry
TFPC for Beginners
Recommended Pool Chemicals
How to Chlorinate Your Pool
Cost Comparison of Chlorine
Also a must for anyone is:
Recommended Levels
Chlorine / CYA chart
Pool Math
Hope this is helpful!
FC - Free Chlorine
Chlorine sanitizes your pool, killing bacteria, germs, and algae. Chlorine is used up in the process of keeping your pool safe, and is also consumed by sunlight. You need to add new chlorine regularly to maintain appropriate levels.
Maintaining an appropriate FC level is the most important part of keeping your water in balance. It is important that you do not allow FC to get too low, or you run the risk of getting algae. If FC gets down to zero, or you have algae, the pool is not safe to swim in.
Free chlorine shows the level of disinfecting chlorine available (active plus reserve) to keep your pool sanitary. FC should be tested, and chlorine added daily. If you have an automatic feeder or SWG, you can test it every couple of days. FC is consumed by sunlight, and by breaking down organic material in your pool. The level of FC you need to maintain depends on your CYA level and how much you use the pool. See the Chlorine / CYA Chart for guidelines on the appropriate FC level to maintain based on your CYA level.
Increase Free Chlorine
Liquid chlorine
5.25% Bleach 5.0% (also adds 0.82 ppm extra salt)
6.0% Bleach 5.7% (also adds 0.82 ppm extra salt)
10.0% Chlorinating Liquid 8.8% (also adds 0.82 ppm extra salt)
12.5% Chlorinating Liquid 10.8% (also adds 0.82 ppm extra salt)
Household bleach and liquid pool chlorine are the two common sources. They are identical in every aspect except strength, household bleach is typically 8.25% and pool chlorine is usually around 12%.
Bleach is sodium hypochlorite, the exact same chemical that many commercial pools use to sanitize their pools.This is your chlorine source for both daily chlorination and SLAMing.
You want common household bleach, without any additives or special features, typically labeled unscented or "original scent". Bleach is available in various strengths, labeled by percentage. The most common strength is 8.25%. The higher the percentage, the less you need.
Liquid chlorine is exactly the same chemical as bleach. It is normally sold in higher concentrations, typically 10% or 12.5%, which are easier to carry than bleach. Liquid chlorine is not available in all areas. Ask your pool store if they carry it. Liquid chlorine is often less expensive than bleach, once you take it's higher strength into account.
Bleach loses strength over time, more quickly when it has a higher percentage and when it is stored at higher temperatures. You should store bleach in a cool dark place. 6% bleach can reasonably be stored for about six months. 12.5% bleach can reasonably be stored for about one month. After that time it is still usable, but will have lost some of it's strength.
Bleach should be added to the pool by pouring slowly in front of a return jet with the pump running. You should pour slowly enough that pouring an entire jug takes more than one minute, preferably two minutes. Leave the pump running for at least 30 minutes after adding bleach.
Dichlor (also large increase CYA and smaller drop in pH)
= Sodium dichloro-s-triazinetirone
= Sodium dichloroisocyanurate
=Sodium dichloroisocyanurate dihydrate
Dichlor Dihydrate 55.4% (also adds 0.91 ppm Cyanruic Acid, CYA)
Dichlor Anhydrous 64.5% (also adds 0.91 ppm Cyanruic Acid, CYA)
It will add .9 parts CYA for every 1 part chlorine it adds.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
A stabilized, granular, fast-dissolving form of chlorine (chlorinated isocyanurate). Because of it's fast dissolving nature it is sometimes sold as 'shock' (not a good idea since it will raise CYA levels fairly quickly).
It is mildly acidic and will lower pH and TA.
Trichlor (also increase CYA and larger drop in pH)
= trichloro-s-triazinetrione
= trichloroisocyanuric acid
Trichlor Tabs/Pucks 91.5% (also adds 0.61 ppm Cyanuric Acid, CYA)
Very acidic, can effect PH levels.
It will add .6 part CYA for every 1 part of chlorine it adds.
For every 10 ppm Free Chlorine it also increases Cyanuric Acid (CYA) by 6 ppm.
A stabilized form of chlorine (chlorinated isocyanurate) usually sold in tablet or stick form for use in automatic chlorinators or in floating dispensers since it is very slow dissolving. It has a very low pH and will lower pH and TA.
Commonly sold as tablets or pucks that you simply put into an automatic container that passes pool water over them and they slowly dissolve - putting chlorine and CYA into your water and lowers the pH. They are incredibly convenient and incredibly insidious. The CYA that they put into your pool water doesn't get used up, and instead accumulates. Eventually the CYA level will build up to a point that renders your chlorine ineffective. Typically, everything is fine, until one day you start to develop algae and don't understand why.
Calcium Hypo
48% Cal-Hypo 47.6% (also adds 0.71 ppm Calcium Hardness, CH; 0.2 ppm extra salt?)
65% Cal-Hypo 64.5% (also adds 0.71 ppm Calcium Hardness, CH; 0.2 ppm extra salt)
73% Cal-Hypo 72.4% (also adds 0.71 ppm Calcium Hardness, CH; 0.2 ppm extra salt)
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by 7 ppm.
A slow dissolving unstabilized chlorine in powder or granular form. It has minimal impact on pH but it will raise calcium hardness with continued use. Suitable for normal sanitation or SLAMing and is the most common form of chlorine sold as "Shock". It can cloud your water if your TA is high and it is recommended to premix it in a bucket of water before adding to your pool. Relatively inexpensive. It is sold in different strengths with 48% and 65% being the most common. 2.5 oz of the 65% stuff will raise 1000 gallons 1 ppm FC.
A convenient, usually powdered, form of chlorine. It's big advantage, like trichlor pucks, is it's convenience. Long term, that convenience makes you pay a price. Roughly 1/3 of Cal-hypo is Calcium that, again, goes into your pool water and you can't get it out. Constant use of cal-hypo usually results in the calcium level getting way too high in your pool which can cause scaling or cloudiness.
Usually granular or pressed tablet chlorine with calcium.
Pros- Doesn't contain stabilizer so no build up issues. Added calcium can protect plaster etc. pool walls and floor. Low impact on PH.
Cons- Very slow dissolving, can damage vinyl liners. Calcium content can add to TDS and cause hazy waterat certain PH and TA levels until filtered out. Filtering out can cause a hard build up on DE filters that makes a breakdown and manual cleaning necessary, causing pool downtime (personal experience).
Lithium Hypo
Lithium Hypochlorite 35.2% (also adds 0.76 ppm extra salt)
A fast dissolving unstabilized chlorine in powder form. It has minimal impact on pH or other water parameters. It is suitable for SLAMing or normal sanitation. It's convenience as a powder is offset by it's extremely high cost!
A convenient powdered form of chlorine. Like liquid chlorine it doesn't add anything that will cause problems to the water.
However, it is generally far more expensive than any other form of chlorine.
Pros- Very fast dissolving. Low impact on PH. No added stabilizer. Cons- Most expensive source of chlorine available.
SWGs (salt water chlorine generators)
Installed in your circulatory system and electrically powered, SWGs produce chlorine from the salt that you have added to your pool. A different article, Salt Water Chlorine Generators, covers them more thoroughly. Briefly, ease of use is by far their single best feature. The large initial investment to purchase the system is their big drawback.
CC - Combined Chlorine
Combined chlorine is an intermediate breakdown product created in the process of sanitizing the pool. CC causes the "chlorine" smell many people associate with chlorine pools. If CC is above 0.5ppm, you should SLAM your pool. CC indicates that there is something in the water that the FC is in the process of breaking down. In an outdoor pool, CC will normally stay at or near zero as long as you maintain an appropriate FC level and the pool gets some direct sunlight.
Potassium monopersulfate (a common non-chlorine shock) will show up on FAS-DPD chlorine tests as CC. There is a special reagent you can get to neutralize the potassium monopersulfate so you can get a true CC reading.
CYA - Cyanuric Acid
Protects chlorine from sunlight and determines the required FC level. (outdoors 30 to 50ppm, SWG 70 to 80ppm, indoors 0 to 20ppm)
Sometimes called stabilizer or conditioner, it helps protect the chlorine from 'burning off' in direct sunlight. Too little and most of your chlorine can be lost in about 30 minutes of direct sun. Too much and it interferes with your chlorine's ability to sanitizer and kill algae. For outdoor pools the recommended range is 30-50 ppm unless you have a salt water chlorine generator, then the recommended range is 70-80 ppm. For indoor pools the recommended target is around 20 ppm.
Cyanuric acid, often called stabilizer or conditioner, both protects FC from sunlight and lowers the effective strength of the FC (by holding some of the FC in reserve). The higher your CYA level, the more FC you need to use to get the same effect. It is important to know your CYA level so you can figure out what FC level to aim for. If you don't have a SWG, CYA is typically kept between 30 and 50ppm. If you have a SWG, CYA is typically kept between 70 and 80ppm.
CYA protects chlorine from the effects of sunlight. The more CYA you have the less chlorine you will lose to sunlight each day. CYA also reduces the effective strength of the chlorine. At higher CYA levels you need more chlorine to maintain the same active chlorine level. If you have a SWG or get extreme amounts of direct sunlight on the pool, adjust CYA to between 60 and 80. Otherwise adjust CYA to between 30 and 50.
Increase CYA
CYA can be increased by adding cyanuric acid, often sold as stabilizer or conditioner. CYA is available as a solid and as a liquid. The liquid costs a lot more, and generally isn't worth the extra expense.
CYA is just about the only chemical you may need to go to a pool store to get although it is sometimes available at Lowe's or Home Depot. Check the label to be sure you are getting cyanuric acid since there are other products that use the words stabilizer and conditioner in their names.
Solid stabilizer is best added by placing it in a sock in the skimmer basket. The pump should be run for 24 hours after adding solid stabilizer and you should avoid backwashing/cleaning the filter for a week. Test and dose chemicals in your pool assuming the amount of CYA added is in the pool according to Poolmath. CYA can be tested the day after it is fully dissolved from the sock.
CYA can be raised with cyanuric acid. Cyanuric acid is sold under a variety of names, including Stabilizer, Conditioner, Instant Pool Water Conditioner, Stabilizer 100, Stabilizer & Conditioner, etc. Instant Pool Water Conditioner is a liquid product which is significantly more expensive than the other forms.
Solid/granular cyanuric acid (CYA) should be placed in a sock and the sock put in the skimmer basket or suspended in front of a pool return. After adding CYA you should leave the pump running for 24 hours and not backwash/clean the filter for a week. Squeezing the sock periodically will help it to dissolve faster. Test and dose chemicals in your pool assuming the amount of CYA added is in the pool according to Poolmath. CYA can be tested the day after it is fully dissolved from the sock.
Decrease CYA
In nearly all cases the best way to lower CYA is to replace water. If replacement water is extremely expensive you might want to look into a reverse osmosis water treatment.
pH - Acidity/Basicity
Needs to be kept in balance to prevent irritation and protect the pool equipment. (7.2 to 7.8)
PH indicates how acidic or basic the water is. PH should be tested daily at first. Once you gain experience with your pool, less frequent monitoring may be appropriate, depending on your pool's typical rate of PH change. A PH level of 7.7 and 7.8 is ideal, but really anything between 7.2 and 7.8 is doing fine, while levels between 7.2 and 8.0 are acceptable for swimming.
PH is a measure of how acidic or basic the water is. PH below 7.0 can damage the pool surface and many pool heaters as well as causing eye and skin irritation. PH above 8.0 can lead to metal stains, plaster scaling, as well as eye and skin irritation. PH should always be maintained between 7.2 and 7.8, ideally between 7.5 and 7.8.
PH levels below 7.2 tend to make eyes sting or burn. PH below 6.8 can cause damage to metal parts, particularly pool heaters with copper heat exchange coils. High PH can lead to calcium scaling.
Many pools will drift up towards higher PH over time. This is particularly true for fresh plaster (particularly in the first month and continuing for perhaps a year) or when TA is high and the water is being aerated (because of a spa, waterfall, fountain, SWG, rain, kids splashing in the pool, etc).
Increase pH
PH can be raised in three ways: borax, soda ash, and aeration. Borax is usually the best choice. Borax raises the PH and also raises the TA level just a little. If your TA level is low soda ash will raise both the PH and TA levels. If your TA level is high, aeration is best as it will not raise the TA level at all. However, aeration is rather slow compared to the other two.
Aeration
Aeration can be provided by a SWG, spa jets, waterfall, fountain, return pointed up so it breaks the surface, air compressor, kids splashing, rain, etc. It can take some time for aeration to raise the PH. The higher your TA level, the faster aeration will work.
Soda ash = ARM & HAMMER® Super Washing Soda Detergent Booster (increases pH and TA)
Do not confuse this with ARM & HAMMER® laundry detergent! It is sold in the laundry detergent section of most larger grocery stores and some big box stores. It is also sold by pool stores under various names, including PH Increaser, PH Up, Balance Pak 200, etc. Soda ash is best added by pre-dissolving it in a bucket of water and then pouring that slowly in front of a return.
Borax = Sodium Tetraborate (increased pH and TA a little)
This is sold at some pool stores under names like Bioguard's Optimizer and ProTeam's Supreme. sodium tetraborate pentahydrate as a pool additive under such names as Proteam's Supreme, Bioguard's Optimizer Plus, Poollife Endure, Guardex Maximizer, and others.
They sell it as a 'water conditioner' to help stabilize pH and prevent algae and in higher concentrations it is algaestatic (an algae preventative rather than a cure). The common name for it is Borax (yep, the 20 Mule Team stuff in the green box you can find in the Laundry aisle of your grocery store) and it's BEST use is to raise pH when it is low without upsetting other water balance measurements (like the pH Increaser from the pool store is prone to do!) Once you get the hang of taking care of your pool you can also use Borax to do exactly the same thing as the expensive pool store products, as an algaestatic agent and water conditioner!
PH can be raised by adding borax. Borax is best added by pre-dissolving it in a bucket of water and then pouring that slowly in front of a return. Borax is available at most grocery stores and places like WalMart and Target. Look for 20 Mule Team Borax, sold as a laundry booster, in a green box in the laundry aisle.
Borax is available as 20 Mule Team® Borax Natural Laundry Booster. It is sold in the laundry detergent section of most larger grocery stores and some big box stores. Borax is best added by pre-dissolving it in a bucket of water and then pouring that slowly in front of a return.
Decrease pH
For lowering PH use either muriatic acid (preferred) or dry acid.
To lower PH you can use either muriatic acid or dry acid. Muriatic acid is less expensive, though it can be annoying to handle. It is best to use muriatic acid if you have a SWG. If you don't have a SWG, and handling muriatic acid bothers you, you can use dry acid.
Muriatic acid
Muriatic acid is sold at places like Home Depot, Lowes, and local hardware stores. It is often out near the pool supplies but sometimes is in the paint section.
Muriatic acid is sold by most hardware stores and some paint stores. The big box hardware stores, like Home Depot and Lowes, almost always have it, but they seem to put it in different departments from store to store. Sometimes it is outside in the garden department, sometimes in pool supplies, and sometimes in the paint department.
Muriatic acid is available in various strengths. The most common strength is called either 20° baume or 31.45%. 10° baume or 15.725% is easier to handle but you need twice as much and it is usually more expensive.
You should always wear eye protection when handling muriatic acid. You do not want to breathe muriatic acid fumes. If you spill any on your clothes it will cause damage. Muriatic acid may sting a bit if you get it on your skin, but won't normally cause any serious harm as long as you rinse it off right away.
Muriatic acid should be added to the pool by pouring slowly in front of a return jet with the pump running. You should pour slowly enough that pouring an entire jug takes more than two minutes. Leave the pump running for at least 30 minutes after adding muriatic acid.
Dry acid
Dry acid is sold by pool stores and the pool departments of some big box stores.
Dry acid is easier to work with than muriatic acid but costs more and should not be used with a SWG. Dry acid is sold by pool stores as PH Down, Lo-n-Slo, and PH Reducer.
Dry acid is best added by pre-dissolving it in a bucket of water and then pouring that slowly in front of a return.
TA - Total Alkalinity
Appropriate levels help keep the pH in balance. High levels can cause pH to rise. (60 to 120ppm, sometimes higher)
TA is sometimes called carbonate hardness or kH. It has nothing to do with water hardness. This is a measure of the carbonates and bicarbonates in your water that help keep your pH from swinging up and down. It is tested with a titration (drop counting) test that has a distinct color change from green to red or from blue to light yellow, depending on your test kit.
Total alkalinity indicates the water's ability to buffer PH changes. Buffering means you need to use a larger quantity of a chemical to change the PH. At low TA levels, the PH tends to swing around wildly. At high TA levels, the PH tends to drift up.
TA is a buffer that helps you maintain your current PH. The higher your TA is, the more difficult it will be to change the PH. However, higher TA levels combined with aeration will tend to raise the PH. The ideal TA level depends on your source of chlorine, and in many cases doesn't need to be at all exact. The usual range is between 60 and 90, though slightly lower and noticeably higher numbers are acceptable in some situations.
Increase Total Alkalinity
TA is raised by adding baking soda.
Baking Soda = Sodium Bicarbonate
Sometimes called Sodium Hydrogen Carbonate, exactly the same chemical no matter what the pool store clerk might tell you! It is used to raise Total Alkalinity. At the pool store they call it Alkalinity Increaser and it's somewhat expensive. At the grocery store it is Baking Soda (yes, the stuff in the orange box from Arm and Hammer in the baking aisle!)
Baking soda is common household baking soda from the baking aisle of any grocery store. If you can find them, larger containers are less expensive per pound and easier to handle. Some larger grocery stores sell baking soda in 4 lb boxes and some big box stores have it in 12 lb bags.
It is often best to make large TA adjustments in a couple of steps, testing the water after each one, as adding large quantities of baking soda can raise the PH a little and you don't want the PH going out of range.
Baking soda can be added by spreading it across the surface of the deep end of the pool.
Decrease Total Alkalinity
There are two reasons to lower your total alkalinity (TA) right away, because you want to slow down the rate that the PH rises, or if high TA is contributing to a high calcium saturation index (CSI) which puts you at risk of calcium scaling. You shouldn't lower TA just to reach a target number. Make sure you actually have one of the above issues before lowering your TA.
The acid/aeration process to lower TA:
1. Add acid to lower your PH to between 7.0 and 7.2 (this also lowers TA)
2. Aerate until PH rises to around 7.6 (the only way to raise PH without also raising TA)
3. Repeat steps 1 and 2 until you reach the desired TA.
You can lower PH with muriatic acid or dry acid/PH Reducer. You can get an estimate of the amount of acid to use with PoolMath. Keep in mind that the amount of acid required can vary from the estimate. If your test kit includes the acid demand test, you can use that to calculate the amount of acid required more precisely. Allow at least 30 minutes after adding acid, with the pump running, before testing the PH again.
Aeration can be provided by a SWG, spa jets, waterfall, fountain, return pointed up so it breaks the surface, air compressor, kids splashing, rain, etc.
Lowering TA can take some time, days or even weeks, depending on the amount of aeration you have and how far you need to lower your TA. Many smaller bubbles are better than a few large bubbles. Lowering the PH back to 7.0-7.2 more frequently will also speed up the process, though that can get tedious.
It is actually the acid which lowers TA. Adding acid lowers both the PH and the TA. Then aeration raises the PH without changing TA. Do not use chemicals to raise your pH during this procedure (unless your pH accidentally goes way too low); that will just raise your TA back up, which is exactly what you are trying to avoid.
There is a common myth that you can lower TA by adding "slugs" of acid to the pool. While any addition of acid, slugs or otherwise, will lower the TA, adding slugs of acid can damage the pool surface and may lower the PH far enough to cause other problems. See this paperfor a detailed study showing that this approach does not work any differently than any other way of adding acid.
To lower TA, you bring the PH down to between 7.0 and 7.2 with acid and then aerate the pool to raise the PH back up. Aeration can come from from a waterfall, fountain, spa jets, kids splashing, SWG, rain, air compressor, or by pointing a return up to the surface so it breaks the surface. That cycle, acid and aeration, is then repeated as many times as is needed to lower TA to where you want it.
CH - Calcium Hardness
Appropriate levels help prevent plaster damage. High levels can cause calcium scaling. (220 to 350ppm, vinyl lower)
Calcium hardness indicates the amount of calcium in the water. Over time, water with low calcium levels will tend to dissolve calcium out of plaster, pebble, tile, stone, concrete, and to some extent fiberglass surfaces. You can prevent this from happening by keeping the water saturated with calcium. In a vinyl liner pool there is no need for calcium, though high levels can still cause problems. A plaster pool without a SWG should have CH levels between 250 and 350 if possible. With a SWG, CH should be kept between 350 to 450. Calcium helps fiberglass pools resist staining and cobalt spotting. If you have a spa you might want to keep CH at at least 100 to 150 to reduce foaming.
This is the amount of calcium in your water and is most important if you have a plaster pool (marcite, exposed aggregate, quartz, etc.). It is not as important in vinyl pools. In fiberglass pools it helps prevent staining and cobalt spotting. Too high a calcium level can lead to scaling and cloudy water, too low can damage plaster surfaces. The recommended range is between 200-400 ppm for both plaster and fiberglass. It really is not an issue for vinyl pools unless it is very high. Anything above about 130 ppm is probably ok for vinyl and above 200 ppm for fiberglass.
Increase Calcium Hardness
You increase CH with calcium chloride, sold as a deicer and by pool stores, or calcium chloride dihydrate, sold by pools stores for increasing calcium.
Decrease Calcium Hardness
You lower calcium by replacing water or using a reverse osmosis water treatment.
Salt
Salt is required with a SWG. Salt can also be added to the water to enhance the subjective feel of the water. For a SWG, check the manual for the correct salt level for your unit. This level will typically around 3,000, but different models vary. For improved water feel without a SWG, try levels around 2,000ppm. These levels are less then one tenth of the salt level in ocean water, which has around 35,000 ppm of salt. People vary in their ability to taste low levels of salt. A few people can taste salt levels as low as 1,000ppm, others not until 3,500ppm or more.
Salt is required by a SWG and can also be used without a SWG to improve the feel of the water. Salt can be dumped directly into the pool as long as you brush it around into a thin layer and leave the pump running for several hours. Use solar salt, sold for water softeners, to raise the salt level. Water softener salt is sold by places like Home Depot and Lowes. Look for salt crystals in the blue bags. Avoid iron fighter, rust remover, or any similar additives. You can use potassium chloride but it costs more to begin with and you need to use 17% more to get the same salt level.
Salt can be added using solar salt, sold for use in water softeners (sodium chloride). You want the kind that is 99.4% pure or better and which doesn't have any rust inhibitor or other additives. Crystals are fine. Pellets will work but dissolve slightly more slowly. Pool store salt generally costs more and is more finely ground, but even pellets dissolve quickly enough so that isn't really any advantage.
The best thing to use to raise the salt level is water softener salt. Look for salt that is 99.4% pure or better and doesn't have any rust inhibitor or other additives. The best choices include Diamond Crystal® Solar Salt Extra Coarse Crystals in blue bags, Morton® White Crystal® Water Softener Salt in blue bags, or Diamond Crystal® Sun Gems® Crystals Water Softener Salt in yellow bags.
Water softener salt pellets will also work. Pellets dissolve more slowly, but still dissolve quickly enough to be fine. Pool salt is also fine to use, though it tends to be much more expensive. Potassium chloride will also work, but you need 28% more of it and it is more expensive. Avoid table salt, rock salt, and deicing salt.
Salt can simply be dumped into the pool. Spread it around a bit with a brush so there aren't any large piles, and leave the pump running for 24 hours after adding salt. If you have a SWG, it should be turned off while you are adding salt and for the next 24 hours.
Sodium Chloride, used for Salt Water Chlorine Generators. It usually has a smaller crystal size than water softener solar salt and costs about twice as much. Ordinary water softener solar salt or pellets that have a purity of at least 99.5% and do not have any additives for cleaning water softeners or removing iron are fine to use in your pool and are what most manufacturers of SWGs recommend! The only advantage to pool salt is that it dissolves slightly faster. Do not use food grade salt in a pool under any circumstances. Food grade salt contains yellow prussiate of soda (sodium ferrocyanide) as an anti-caking ingredient and that can cause iron staining in your pool.
All swimming pools contain some salt, since there is some salt in most of the chemicals used swimming pools. Salt, at levels around 2000 ppm, can be used to improve the subjective feel of the water. Most SWGs require salt levels around 3000 ppm, though some require higher levels. Salt can contribute to accelerated corrosion of some materials, especially some of the softer kinds of natural stone and inferior grades of stainless steel. Ocean water typically has salt levels around 35,000 ppm, more than ten times the levels commonly used with a SWG.
Borate
Borates are an optional enhancement that helps control PH drift, keeps algae in check, reduce chlorine usage, and provides various subjective water quality/feel improvements.
The borates are an additional pH buffer, but they more strongly buffer against a rise in pH rather than a drop (in terms of capacity as the pH changes; more on that below).
If you are not intentionally using borates there is no need to test for them. When using borates, the recommended level is between 30 and 50 ppm.
I have done a ton of reading on these forms and have bounced between numerous pinned forms for the information that I needed. After getting a grasp on things, I decided to compile all the information into one place and break it down into sections (Chlorine, CYA, pH, TA, CH) and list what increases and decreases each of these parameters so one can focus in on an issue and know how to address it and what the effects will be.
I do not bring any new information to the table, I just complied the information from:
Definitions and Abbreviations
ABCs of Pool Water Chemistry
TFPC for Beginners
Recommended Pool Chemicals
How to Chlorinate Your Pool
Cost Comparison of Chlorine
Also a must for anyone is:
Recommended Levels
Chlorine / CYA chart
Pool Math
Hope this is helpful!
FC - Free Chlorine
Chlorine sanitizes your pool, killing bacteria, germs, and algae. Chlorine is used up in the process of keeping your pool safe, and is also consumed by sunlight. You need to add new chlorine regularly to maintain appropriate levels.
Maintaining an appropriate FC level is the most important part of keeping your water in balance. It is important that you do not allow FC to get too low, or you run the risk of getting algae. If FC gets down to zero, or you have algae, the pool is not safe to swim in.
Free chlorine shows the level of disinfecting chlorine available (active plus reserve) to keep your pool sanitary. FC should be tested, and chlorine added daily. If you have an automatic feeder or SWG, you can test it every couple of days. FC is consumed by sunlight, and by breaking down organic material in your pool. The level of FC you need to maintain depends on your CYA level and how much you use the pool. See the Chlorine / CYA Chart for guidelines on the appropriate FC level to maintain based on your CYA level.
Increase Free Chlorine
Liquid chlorine
5.25% Bleach 5.0% (also adds 0.82 ppm extra salt)
6.0% Bleach 5.7% (also adds 0.82 ppm extra salt)
10.0% Chlorinating Liquid 8.8% (also adds 0.82 ppm extra salt)
12.5% Chlorinating Liquid 10.8% (also adds 0.82 ppm extra salt)
Household bleach and liquid pool chlorine are the two common sources. They are identical in every aspect except strength, household bleach is typically 8.25% and pool chlorine is usually around 12%.
Bleach is sodium hypochlorite, the exact same chemical that many commercial pools use to sanitize their pools.This is your chlorine source for both daily chlorination and SLAMing.
You want common household bleach, without any additives or special features, typically labeled unscented or "original scent". Bleach is available in various strengths, labeled by percentage. The most common strength is 8.25%. The higher the percentage, the less you need.
Liquid chlorine is exactly the same chemical as bleach. It is normally sold in higher concentrations, typically 10% or 12.5%, which are easier to carry than bleach. Liquid chlorine is not available in all areas. Ask your pool store if they carry it. Liquid chlorine is often less expensive than bleach, once you take it's higher strength into account.
Bleach loses strength over time, more quickly when it has a higher percentage and when it is stored at higher temperatures. You should store bleach in a cool dark place. 6% bleach can reasonably be stored for about six months. 12.5% bleach can reasonably be stored for about one month. After that time it is still usable, but will have lost some of it's strength.
Bleach should be added to the pool by pouring slowly in front of a return jet with the pump running. You should pour slowly enough that pouring an entire jug takes more than one minute, preferably two minutes. Leave the pump running for at least 30 minutes after adding bleach.
Dichlor (also large increase CYA and smaller drop in pH)
= Sodium dichloro-s-triazinetirone
= Sodium dichloroisocyanurate
=Sodium dichloroisocyanurate dihydrate
Dichlor Dihydrate 55.4% (also adds 0.91 ppm Cyanruic Acid, CYA)
Dichlor Anhydrous 64.5% (also adds 0.91 ppm Cyanruic Acid, CYA)
It will add .9 parts CYA for every 1 part chlorine it adds.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
A stabilized, granular, fast-dissolving form of chlorine (chlorinated isocyanurate). Because of it's fast dissolving nature it is sometimes sold as 'shock' (not a good idea since it will raise CYA levels fairly quickly).
It is mildly acidic and will lower pH and TA.
Trichlor (also increase CYA and larger drop in pH)
= trichloro-s-triazinetrione
= trichloroisocyanuric acid
Trichlor Tabs/Pucks 91.5% (also adds 0.61 ppm Cyanuric Acid, CYA)
Very acidic, can effect PH levels.
It will add .6 part CYA for every 1 part of chlorine it adds.
For every 10 ppm Free Chlorine it also increases Cyanuric Acid (CYA) by 6 ppm.
A stabilized form of chlorine (chlorinated isocyanurate) usually sold in tablet or stick form for use in automatic chlorinators or in floating dispensers since it is very slow dissolving. It has a very low pH and will lower pH and TA.
Commonly sold as tablets or pucks that you simply put into an automatic container that passes pool water over them and they slowly dissolve - putting chlorine and CYA into your water and lowers the pH. They are incredibly convenient and incredibly insidious. The CYA that they put into your pool water doesn't get used up, and instead accumulates. Eventually the CYA level will build up to a point that renders your chlorine ineffective. Typically, everything is fine, until one day you start to develop algae and don't understand why.
Calcium Hypo
48% Cal-Hypo 47.6% (also adds 0.71 ppm Calcium Hardness, CH; 0.2 ppm extra salt?)
65% Cal-Hypo 64.5% (also adds 0.71 ppm Calcium Hardness, CH; 0.2 ppm extra salt)
73% Cal-Hypo 72.4% (also adds 0.71 ppm Calcium Hardness, CH; 0.2 ppm extra salt)
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by 7 ppm.
A slow dissolving unstabilized chlorine in powder or granular form. It has minimal impact on pH but it will raise calcium hardness with continued use. Suitable for normal sanitation or SLAMing and is the most common form of chlorine sold as "Shock". It can cloud your water if your TA is high and it is recommended to premix it in a bucket of water before adding to your pool. Relatively inexpensive. It is sold in different strengths with 48% and 65% being the most common. 2.5 oz of the 65% stuff will raise 1000 gallons 1 ppm FC.
A convenient, usually powdered, form of chlorine. It's big advantage, like trichlor pucks, is it's convenience. Long term, that convenience makes you pay a price. Roughly 1/3 of Cal-hypo is Calcium that, again, goes into your pool water and you can't get it out. Constant use of cal-hypo usually results in the calcium level getting way too high in your pool which can cause scaling or cloudiness.
Usually granular or pressed tablet chlorine with calcium.
Pros- Doesn't contain stabilizer so no build up issues. Added calcium can protect plaster etc. pool walls and floor. Low impact on PH.
Cons- Very slow dissolving, can damage vinyl liners. Calcium content can add to TDS and cause hazy waterat certain PH and TA levels until filtered out. Filtering out can cause a hard build up on DE filters that makes a breakdown and manual cleaning necessary, causing pool downtime (personal experience).
Lithium Hypo
Lithium Hypochlorite 35.2% (also adds 0.76 ppm extra salt)
A fast dissolving unstabilized chlorine in powder form. It has minimal impact on pH or other water parameters. It is suitable for SLAMing or normal sanitation. It's convenience as a powder is offset by it's extremely high cost!
A convenient powdered form of chlorine. Like liquid chlorine it doesn't add anything that will cause problems to the water.
However, it is generally far more expensive than any other form of chlorine.
Pros- Very fast dissolving. Low impact on PH. No added stabilizer. Cons- Most expensive source of chlorine available.
SWGs (salt water chlorine generators)
Installed in your circulatory system and electrically powered, SWGs produce chlorine from the salt that you have added to your pool. A different article, Salt Water Chlorine Generators, covers them more thoroughly. Briefly, ease of use is by far their single best feature. The large initial investment to purchase the system is their big drawback.
CC - Combined Chlorine
Combined chlorine is an intermediate breakdown product created in the process of sanitizing the pool. CC causes the "chlorine" smell many people associate with chlorine pools. If CC is above 0.5ppm, you should SLAM your pool. CC indicates that there is something in the water that the FC is in the process of breaking down. In an outdoor pool, CC will normally stay at or near zero as long as you maintain an appropriate FC level and the pool gets some direct sunlight.
Potassium monopersulfate (a common non-chlorine shock) will show up on FAS-DPD chlorine tests as CC. There is a special reagent you can get to neutralize the potassium monopersulfate so you can get a true CC reading.
CYA - Cyanuric Acid
Protects chlorine from sunlight and determines the required FC level. (outdoors 30 to 50ppm, SWG 70 to 80ppm, indoors 0 to 20ppm)
Sometimes called stabilizer or conditioner, it helps protect the chlorine from 'burning off' in direct sunlight. Too little and most of your chlorine can be lost in about 30 minutes of direct sun. Too much and it interferes with your chlorine's ability to sanitizer and kill algae. For outdoor pools the recommended range is 30-50 ppm unless you have a salt water chlorine generator, then the recommended range is 70-80 ppm. For indoor pools the recommended target is around 20 ppm.
Cyanuric acid, often called stabilizer or conditioner, both protects FC from sunlight and lowers the effective strength of the FC (by holding some of the FC in reserve). The higher your CYA level, the more FC you need to use to get the same effect. It is important to know your CYA level so you can figure out what FC level to aim for. If you don't have a SWG, CYA is typically kept between 30 and 50ppm. If you have a SWG, CYA is typically kept between 70 and 80ppm.
CYA protects chlorine from the effects of sunlight. The more CYA you have the less chlorine you will lose to sunlight each day. CYA also reduces the effective strength of the chlorine. At higher CYA levels you need more chlorine to maintain the same active chlorine level. If you have a SWG or get extreme amounts of direct sunlight on the pool, adjust CYA to between 60 and 80. Otherwise adjust CYA to between 30 and 50.
Increase CYA
CYA can be increased by adding cyanuric acid, often sold as stabilizer or conditioner. CYA is available as a solid and as a liquid. The liquid costs a lot more, and generally isn't worth the extra expense.
CYA is just about the only chemical you may need to go to a pool store to get although it is sometimes available at Lowe's or Home Depot. Check the label to be sure you are getting cyanuric acid since there are other products that use the words stabilizer and conditioner in their names.
Solid stabilizer is best added by placing it in a sock in the skimmer basket. The pump should be run for 24 hours after adding solid stabilizer and you should avoid backwashing/cleaning the filter for a week. Test and dose chemicals in your pool assuming the amount of CYA added is in the pool according to Poolmath. CYA can be tested the day after it is fully dissolved from the sock.
CYA can be raised with cyanuric acid. Cyanuric acid is sold under a variety of names, including Stabilizer, Conditioner, Instant Pool Water Conditioner, Stabilizer 100, Stabilizer & Conditioner, etc. Instant Pool Water Conditioner is a liquid product which is significantly more expensive than the other forms.
Solid/granular cyanuric acid (CYA) should be placed in a sock and the sock put in the skimmer basket or suspended in front of a pool return. After adding CYA you should leave the pump running for 24 hours and not backwash/clean the filter for a week. Squeezing the sock periodically will help it to dissolve faster. Test and dose chemicals in your pool assuming the amount of CYA added is in the pool according to Poolmath. CYA can be tested the day after it is fully dissolved from the sock.
Decrease CYA
In nearly all cases the best way to lower CYA is to replace water. If replacement water is extremely expensive you might want to look into a reverse osmosis water treatment.
pH - Acidity/Basicity
Needs to be kept in balance to prevent irritation and protect the pool equipment. (7.2 to 7.8)
PH indicates how acidic or basic the water is. PH should be tested daily at first. Once you gain experience with your pool, less frequent monitoring may be appropriate, depending on your pool's typical rate of PH change. A PH level of 7.7 and 7.8 is ideal, but really anything between 7.2 and 7.8 is doing fine, while levels between 7.2 and 8.0 are acceptable for swimming.
PH is a measure of how acidic or basic the water is. PH below 7.0 can damage the pool surface and many pool heaters as well as causing eye and skin irritation. PH above 8.0 can lead to metal stains, plaster scaling, as well as eye and skin irritation. PH should always be maintained between 7.2 and 7.8, ideally between 7.5 and 7.8.
PH levels below 7.2 tend to make eyes sting or burn. PH below 6.8 can cause damage to metal parts, particularly pool heaters with copper heat exchange coils. High PH can lead to calcium scaling.
Many pools will drift up towards higher PH over time. This is particularly true for fresh plaster (particularly in the first month and continuing for perhaps a year) or when TA is high and the water is being aerated (because of a spa, waterfall, fountain, SWG, rain, kids splashing in the pool, etc).
Increase pH
PH can be raised in three ways: borax, soda ash, and aeration. Borax is usually the best choice. Borax raises the PH and also raises the TA level just a little. If your TA level is low soda ash will raise both the PH and TA levels. If your TA level is high, aeration is best as it will not raise the TA level at all. However, aeration is rather slow compared to the other two.
Aeration
Aeration can be provided by a SWG, spa jets, waterfall, fountain, return pointed up so it breaks the surface, air compressor, kids splashing, rain, etc. It can take some time for aeration to raise the PH. The higher your TA level, the faster aeration will work.
Soda ash = ARM & HAMMER® Super Washing Soda Detergent Booster (increases pH and TA)
Do not confuse this with ARM & HAMMER® laundry detergent! It is sold in the laundry detergent section of most larger grocery stores and some big box stores. It is also sold by pool stores under various names, including PH Increaser, PH Up, Balance Pak 200, etc. Soda ash is best added by pre-dissolving it in a bucket of water and then pouring that slowly in front of a return.
Borax = Sodium Tetraborate (increased pH and TA a little)
This is sold at some pool stores under names like Bioguard's Optimizer and ProTeam's Supreme. sodium tetraborate pentahydrate as a pool additive under such names as Proteam's Supreme, Bioguard's Optimizer Plus, Poollife Endure, Guardex Maximizer, and others.
They sell it as a 'water conditioner' to help stabilize pH and prevent algae and in higher concentrations it is algaestatic (an algae preventative rather than a cure). The common name for it is Borax (yep, the 20 Mule Team stuff in the green box you can find in the Laundry aisle of your grocery store) and it's BEST use is to raise pH when it is low without upsetting other water balance measurements (like the pH Increaser from the pool store is prone to do!) Once you get the hang of taking care of your pool you can also use Borax to do exactly the same thing as the expensive pool store products, as an algaestatic agent and water conditioner!
PH can be raised by adding borax. Borax is best added by pre-dissolving it in a bucket of water and then pouring that slowly in front of a return. Borax is available at most grocery stores and places like WalMart and Target. Look for 20 Mule Team Borax, sold as a laundry booster, in a green box in the laundry aisle.
Borax is available as 20 Mule Team® Borax Natural Laundry Booster. It is sold in the laundry detergent section of most larger grocery stores and some big box stores. Borax is best added by pre-dissolving it in a bucket of water and then pouring that slowly in front of a return.
Decrease pH
For lowering PH use either muriatic acid (preferred) or dry acid.
To lower PH you can use either muriatic acid or dry acid. Muriatic acid is less expensive, though it can be annoying to handle. It is best to use muriatic acid if you have a SWG. If you don't have a SWG, and handling muriatic acid bothers you, you can use dry acid.
Muriatic acid
Muriatic acid is sold at places like Home Depot, Lowes, and local hardware stores. It is often out near the pool supplies but sometimes is in the paint section.
Muriatic acid is sold by most hardware stores and some paint stores. The big box hardware stores, like Home Depot and Lowes, almost always have it, but they seem to put it in different departments from store to store. Sometimes it is outside in the garden department, sometimes in pool supplies, and sometimes in the paint department.
Muriatic acid is available in various strengths. The most common strength is called either 20° baume or 31.45%. 10° baume or 15.725% is easier to handle but you need twice as much and it is usually more expensive.
You should always wear eye protection when handling muriatic acid. You do not want to breathe muriatic acid fumes. If you spill any on your clothes it will cause damage. Muriatic acid may sting a bit if you get it on your skin, but won't normally cause any serious harm as long as you rinse it off right away.
Muriatic acid should be added to the pool by pouring slowly in front of a return jet with the pump running. You should pour slowly enough that pouring an entire jug takes more than two minutes. Leave the pump running for at least 30 minutes after adding muriatic acid.
Dry acid
Dry acid is sold by pool stores and the pool departments of some big box stores.
Dry acid is easier to work with than muriatic acid but costs more and should not be used with a SWG. Dry acid is sold by pool stores as PH Down, Lo-n-Slo, and PH Reducer.
Dry acid is best added by pre-dissolving it in a bucket of water and then pouring that slowly in front of a return.
TA - Total Alkalinity
Appropriate levels help keep the pH in balance. High levels can cause pH to rise. (60 to 120ppm, sometimes higher)
TA is sometimes called carbonate hardness or kH. It has nothing to do with water hardness. This is a measure of the carbonates and bicarbonates in your water that help keep your pH from swinging up and down. It is tested with a titration (drop counting) test that has a distinct color change from green to red or from blue to light yellow, depending on your test kit.
Total alkalinity indicates the water's ability to buffer PH changes. Buffering means you need to use a larger quantity of a chemical to change the PH. At low TA levels, the PH tends to swing around wildly. At high TA levels, the PH tends to drift up.
TA is a buffer that helps you maintain your current PH. The higher your TA is, the more difficult it will be to change the PH. However, higher TA levels combined with aeration will tend to raise the PH. The ideal TA level depends on your source of chlorine, and in many cases doesn't need to be at all exact. The usual range is between 60 and 90, though slightly lower and noticeably higher numbers are acceptable in some situations.
Increase Total Alkalinity
TA is raised by adding baking soda.
Baking Soda = Sodium Bicarbonate
Sometimes called Sodium Hydrogen Carbonate, exactly the same chemical no matter what the pool store clerk might tell you! It is used to raise Total Alkalinity. At the pool store they call it Alkalinity Increaser and it's somewhat expensive. At the grocery store it is Baking Soda (yes, the stuff in the orange box from Arm and Hammer in the baking aisle!)
Baking soda is common household baking soda from the baking aisle of any grocery store. If you can find them, larger containers are less expensive per pound and easier to handle. Some larger grocery stores sell baking soda in 4 lb boxes and some big box stores have it in 12 lb bags.
It is often best to make large TA adjustments in a couple of steps, testing the water after each one, as adding large quantities of baking soda can raise the PH a little and you don't want the PH going out of range.
Baking soda can be added by spreading it across the surface of the deep end of the pool.
Decrease Total Alkalinity
There are two reasons to lower your total alkalinity (TA) right away, because you want to slow down the rate that the PH rises, or if high TA is contributing to a high calcium saturation index (CSI) which puts you at risk of calcium scaling. You shouldn't lower TA just to reach a target number. Make sure you actually have one of the above issues before lowering your TA.
The acid/aeration process to lower TA:
1. Add acid to lower your PH to between 7.0 and 7.2 (this also lowers TA)
2. Aerate until PH rises to around 7.6 (the only way to raise PH without also raising TA)
3. Repeat steps 1 and 2 until you reach the desired TA.
You can lower PH with muriatic acid or dry acid/PH Reducer. You can get an estimate of the amount of acid to use with PoolMath. Keep in mind that the amount of acid required can vary from the estimate. If your test kit includes the acid demand test, you can use that to calculate the amount of acid required more precisely. Allow at least 30 minutes after adding acid, with the pump running, before testing the PH again.
Aeration can be provided by a SWG, spa jets, waterfall, fountain, return pointed up so it breaks the surface, air compressor, kids splashing, rain, etc.
Lowering TA can take some time, days or even weeks, depending on the amount of aeration you have and how far you need to lower your TA. Many smaller bubbles are better than a few large bubbles. Lowering the PH back to 7.0-7.2 more frequently will also speed up the process, though that can get tedious.
It is actually the acid which lowers TA. Adding acid lowers both the PH and the TA. Then aeration raises the PH without changing TA. Do not use chemicals to raise your pH during this procedure (unless your pH accidentally goes way too low); that will just raise your TA back up, which is exactly what you are trying to avoid.
There is a common myth that you can lower TA by adding "slugs" of acid to the pool. While any addition of acid, slugs or otherwise, will lower the TA, adding slugs of acid can damage the pool surface and may lower the PH far enough to cause other problems. See this paperfor a detailed study showing that this approach does not work any differently than any other way of adding acid.
To lower TA, you bring the PH down to between 7.0 and 7.2 with acid and then aerate the pool to raise the PH back up. Aeration can come from from a waterfall, fountain, spa jets, kids splashing, SWG, rain, air compressor, or by pointing a return up to the surface so it breaks the surface. That cycle, acid and aeration, is then repeated as many times as is needed to lower TA to where you want it.
CH - Calcium Hardness
Appropriate levels help prevent plaster damage. High levels can cause calcium scaling. (220 to 350ppm, vinyl lower)
Calcium hardness indicates the amount of calcium in the water. Over time, water with low calcium levels will tend to dissolve calcium out of plaster, pebble, tile, stone, concrete, and to some extent fiberglass surfaces. You can prevent this from happening by keeping the water saturated with calcium. In a vinyl liner pool there is no need for calcium, though high levels can still cause problems. A plaster pool without a SWG should have CH levels between 250 and 350 if possible. With a SWG, CH should be kept between 350 to 450. Calcium helps fiberglass pools resist staining and cobalt spotting. If you have a spa you might want to keep CH at at least 100 to 150 to reduce foaming.
This is the amount of calcium in your water and is most important if you have a plaster pool (marcite, exposed aggregate, quartz, etc.). It is not as important in vinyl pools. In fiberglass pools it helps prevent staining and cobalt spotting. Too high a calcium level can lead to scaling and cloudy water, too low can damage plaster surfaces. The recommended range is between 200-400 ppm for both plaster and fiberglass. It really is not an issue for vinyl pools unless it is very high. Anything above about 130 ppm is probably ok for vinyl and above 200 ppm for fiberglass.
Increase Calcium Hardness
You increase CH with calcium chloride, sold as a deicer and by pool stores, or calcium chloride dihydrate, sold by pools stores for increasing calcium.
Decrease Calcium Hardness
You lower calcium by replacing water or using a reverse osmosis water treatment.
Salt
Salt is required with a SWG. Salt can also be added to the water to enhance the subjective feel of the water. For a SWG, check the manual for the correct salt level for your unit. This level will typically around 3,000, but different models vary. For improved water feel without a SWG, try levels around 2,000ppm. These levels are less then one tenth of the salt level in ocean water, which has around 35,000 ppm of salt. People vary in their ability to taste low levels of salt. A few people can taste salt levels as low as 1,000ppm, others not until 3,500ppm or more.
Salt is required by a SWG and can also be used without a SWG to improve the feel of the water. Salt can be dumped directly into the pool as long as you brush it around into a thin layer and leave the pump running for several hours. Use solar salt, sold for water softeners, to raise the salt level. Water softener salt is sold by places like Home Depot and Lowes. Look for salt crystals in the blue bags. Avoid iron fighter, rust remover, or any similar additives. You can use potassium chloride but it costs more to begin with and you need to use 17% more to get the same salt level.
Salt can be added using solar salt, sold for use in water softeners (sodium chloride). You want the kind that is 99.4% pure or better and which doesn't have any rust inhibitor or other additives. Crystals are fine. Pellets will work but dissolve slightly more slowly. Pool store salt generally costs more and is more finely ground, but even pellets dissolve quickly enough so that isn't really any advantage.
The best thing to use to raise the salt level is water softener salt. Look for salt that is 99.4% pure or better and doesn't have any rust inhibitor or other additives. The best choices include Diamond Crystal® Solar Salt Extra Coarse Crystals in blue bags, Morton® White Crystal® Water Softener Salt in blue bags, or Diamond Crystal® Sun Gems® Crystals Water Softener Salt in yellow bags.
Water softener salt pellets will also work. Pellets dissolve more slowly, but still dissolve quickly enough to be fine. Pool salt is also fine to use, though it tends to be much more expensive. Potassium chloride will also work, but you need 28% more of it and it is more expensive. Avoid table salt, rock salt, and deicing salt.
Salt can simply be dumped into the pool. Spread it around a bit with a brush so there aren't any large piles, and leave the pump running for 24 hours after adding salt. If you have a SWG, it should be turned off while you are adding salt and for the next 24 hours.
Sodium Chloride, used for Salt Water Chlorine Generators. It usually has a smaller crystal size than water softener solar salt and costs about twice as much. Ordinary water softener solar salt or pellets that have a purity of at least 99.5% and do not have any additives for cleaning water softeners or removing iron are fine to use in your pool and are what most manufacturers of SWGs recommend! The only advantage to pool salt is that it dissolves slightly faster. Do not use food grade salt in a pool under any circumstances. Food grade salt contains yellow prussiate of soda (sodium ferrocyanide) as an anti-caking ingredient and that can cause iron staining in your pool.
All swimming pools contain some salt, since there is some salt in most of the chemicals used swimming pools. Salt, at levels around 2000 ppm, can be used to improve the subjective feel of the water. Most SWGs require salt levels around 3000 ppm, though some require higher levels. Salt can contribute to accelerated corrosion of some materials, especially some of the softer kinds of natural stone and inferior grades of stainless steel. Ocean water typically has salt levels around 35,000 ppm, more than ten times the levels commonly used with a SWG.
Borate
Borates are an optional enhancement that helps control PH drift, keeps algae in check, reduce chlorine usage, and provides various subjective water quality/feel improvements.
The borates are an additional pH buffer, but they more strongly buffer against a rise in pH rather than a drop (in terms of capacity as the pH changes; more on that below).
If you are not intentionally using borates there is no need to test for them. When using borates, the recommended level is between 30 and 50 ppm.
