Chlorine tablets over chlorinating in-ground-spa. Best way to chlorinate?

[bridgman]

I am understanding the method correctly? Do you switch to bleach and never use Dichor again, as you stated "one switches to using bleach"

In addition to what chem geek said, you would also restart the cycle with dichlor/trichlor each time you drain/refill the spa, since the fill water would have zero CYA.

Edit - jblizzle already said that... um... yesterday. Never mind...

Also, would it make sense to add a liquid or powder stabilizer, such as Cyanuric Acid (CYA) with bleach instead of Dichor? I would think with liquid or powder, you would have more control.

That seems to be the most common recommendation you see here for pools -- add CYA separately and use only bleach -- but dichlor/bleach works really well for spas where the volumes are lower. Dichlor is also handy because it dissolves quickly, which is nice if you drain/refill regularly, although since I started using the dichlor/bleach method I find the water stays nice and clear for months at a time.

Dichlor is a powder (ok, "granules") so you can add a measured amount and calculate how much CYA is going in, and in principle you can keep track of how much dichlor you're adding and switch over to bleach after you have added the amount of dichlor which raises your CYA to the right level.

The trichlor/bleach suggestions are just a way to help you make good use of the tabs you already have. I guess the same idea could work, where you count the number of tabs you add and switch to bleach after the right number, but testing CYA level is still a good idea. The nice thing about stabilizer/bleach or dichlor/bleach or trichlor/bleach is that normally the CYA level doesn't change much after you switch to bleach so you don't need to be frequently testing CYA levels and tweaking target FC levels to match.

Makes things really easy, even for me

 

[norwood451]

This is an interesting statement. "CYA level doesn't change much". So, if I am understanding you correctly, one can add the correct proportional amount of Cyanuric Acid (CYA) to a spa and it will not degrade much overtime? For example, if my CYA levels were very low, which think is true, I can buy full strength CYA and only add bleach and the bleach would hold it's strength.

 

[bridgman]

Yep, that's the idea. As I understand it from reading the other posts here, the CYA levels will drift down a bit over time but the only thing that gets used up quickly is the chlorine -- so ideally all you would want to *add* on a regular basis is chlorine.

Using bleach instead of dichlor/trichlor lets you add chlorine without adding anything else (other than a bit of salt), so most of the time you just add bleach as needed and all of the other levels pretty much stay unchanged. That's what makes the approach so simple and attractive.

The bleach doesn't last long (you need to add some after every use plus every 2-3 days between uses) so it's less convenient than tabs in that respect, but it's simple and works really well. With pools you usually need to add bleach every day but with spas you normally have a cover on and don't lose chlorine to sunlight so you can typically go longer between bleach additions... so I test daily and only add bleach when needed.

Presumably one day someone will invent a new kind of slow-dissolving tab that doesn't add CYA and things will get even easier, but for now I'm happy with the dichlor/bleach approach.

 

[norwood451]

I have been using tricolor since January 1- when I first filled the spa and I tested for the first time for CYA levels Thursday, with the results way under 30ppm. Considering I will now be adding significantly less Trichlor (one 1/8 of a 3" Tablet), and the fact will be months to build up any Cyanuric Acid (CYA), would it make sense to buy full strength CYA to bring up the levels, or not worry about the CYA?

(I posted this before reading the 11:42 Post). So, it appears you do not think CYA is necessary?

 

[bridgman]

Sorry, didn't mean to imply that CYA wasn't necessary, just that it doesn't take long to reach the level of CYA you need (IIRC 20-30 ppm is recommended for spas) and using only bleach from that point gives you the chlorine you need without raising CYA any further.

jblizzle posted a link to a really handy table yesterday, link copied below... you can see that for really low CYA levels you need to keep really low (and difficult to manage) levels of chlorine, and at really high CYA levels you need proportionally more chlorine to get the same effect. At 20-30ppm your "good range" is 1-3 ppm of FC, which is pretty easy to maintain.

https://www.troublefreepool.com/~richardfalk/pool/HOCl.htm

Things get interesting when you look at the amount of chlorine you need to add after each use vs the amount of chlorine you want to maintain. Depending on the size of your spa, you might need to add a quantity of chlorine which translates to 3-10 ppm, which is not way out of line from normal FC range if you have a moderate amount of CYA, but which is "scary high" if you have little or no CYA, so 20-30 ppm becomes a bit of a "sweet spot" in that respect. The 30-50 range recommended for pools works too but since the spa is covered most of the time you don't need the extra protection from sunlight that a higher CYA level would give you.

I learned about all this from chem geek's 2007-era posts but it seems that what he posted back then still holds up today.

 

[norwood451]

Sorry, didn't mean to imply that CYA wasn't necessary, just that it doesn't take long to reach the level of CYA you need (IIRC 20-30 ppm is recommended for spas) and using only bleach from that point gives you the chlorine you need without raising CYA any further.

jblizzle posted a link to a really handy table yesterday, link copied below... you can see that for really low CYA levels you need to keep really low (and difficult to manage) levels of chlorine, and at really high CYA levels you need proportionally more chlorine to get the same effect. At 20-30ppm your "good range" is 1-3 ppm of FC, which is pretty easy to maintain.

https://www.troublefreepool.com/~richardfalk/pool/HOCl.htm



Things get interesting when you look at the amount of chlorine you need to add after each use vs the amount of chlorine you want to maintain. Depending on the size of your spa, you might need to add a quantity of chlorine which translates to 3-10 ppm, which is not way out of line from normal FC range if you have a moderate amount of CYA, but which is "scary high" if you have little or no CYA, so 20-30 ppm becomes a bit of a "sweet spot" in that respect. The 30-50 range recommended for pools works too but since the spa is covered most of the time you don't need the extra protection from sunlight that a higher CYA level would give you.

I learned about all this from chem geek's 2007-era posts but it seems that what he posted back then still holds up today.

My spa is not covered and my CYA levels are close to Zero. I will probably not worry about CYA, as it takes so few (1/8 tab) chorine tabs to get to 6ppm FC.

 

[bridgman]

How much water in your spa and how many tabs do you expect to use between drain/refill cycles ?

My tub is 680 gallons, and my impression from a couple of searches is that a 3" trichlor tab typically weighs 7 or 8 ounces. When I plugged 7 oz of trichlor and 680 gallons into PoolMath the result was that by the time you used a full tab you would have raised the CYA by 43 ppm.

7 oz of trichlor also gives 71 oz of FC so using my tub as an example adding 1/8th of a tab each time would take FC up to 9 then it would go back down to zero with usage and time. CYA would go up to 5 or 6 and more-or-less stay there. Each additional 1/8th of a tab would take FC up by 9 then it would go back down, while CYA would go up by another 5.5 each time and not go down other than through overfilling & spillage (apparently it does go down a bit on its own but much more slowly than FC), so CYA would be 43-ish after the first tab, 86-ish after the second tab etc...

If you haven't played with PoolMath yet, there's a section at the bottom called "Effects of adding chemicals", which is either fun or scary depending on what you were thinking of adding

 

[norwood451]

How much water in your spa and how many tabs do you expect to use between drain/refill cycles ?

My tub is 680 gallons, and my impression from a couple of searches is that a 3" trichlor tab typically weighs 7 or 8 ounces. When I plugged 7 oz of trichlor and 680 gallons into PoolMath the result was that by the time you used a full tab you would have raised the CYA by 43 ppm.

7 oz of trichlor also gives 71 oz of FC so using my tub as an example adding 1/8th of a tab each time would take FC up to 9 then it would go back down to zero with usage and time. CYA would go up to 5 or 6 and more-or-less stay there. Each additional 1/8th of a tab would take FC up by 9 then it would go back down, while CYA would go up by another 5.5 each time and not go down other than through overfilling & spillage (apparently it does go down a bit on its own but much more slowly than FC), so CYA would be 43-ish after the first tab, 86-ish after the second tab etc...

If you haven't played with PoolMath yet, there's a section at the bottom called "Effects of adding chemicals", which is either fun or scary depending on what you were thinking of adding

I think there is 850 gallons, but it is odd shaped with seats and hills and valleys, so it is difficult to know without draining and refilling--I forgot to measure the last time I filled.

I think I have dissolved 3 tablets since the fill, but I have overfilled the spa 2 times. The test strip I used was 100% accurate for all of the tests provide, as I cross tested: ph, alk, and total chlorine. The strip provided two additional Tests, FC and stabilizer and the stabilizer was very low- close to zero. It hard to say how low, but certainly under 30ppm. Base on you math, I think it should be higher, but I am not complaining. I think it does not matter about a low CYM, as long as the FC levels are high enough and the advantage to the CYM is to lower pH and keep FC from falling quick. The disadvantage is that it builds up and can cause problems with the FC not working properly or at all.

The take home message for me as been: 1. know what the CYM levels are, 2. I now know that 10ppm total chlorine is ok or my spa, but too high for a pool, 3. Use a smaller-chuck amount of the chlorine tablets, so levels do not go too high. 4 Add bleach, as needed to quickly bring up FC levels. 5. After I run out of tablets, consider a different sanitation method, such as Dichor and bleach. I am sure there is more, but five is enough for now.

 

[chem geek]

I have been using tricolor since January 1- when I first filled the spa and I tested for the first time for CYA levels Thursday, with the results way under 30ppm. Considering I will now be adding significantly less Trichlor (one 1/8 of a 3" Tablet), and the fact will be months to build up any Cyanuric Acid (CYA), would it make sense to buy full strength CYA to bring up the levels, or not worry about the CYA?

Is your bather load low? Part of the reason your CYA is only slowly rising is that your tub is large. If it's really 850 gallons, then every person-hour of soaking in a hot (104ºF) spa would need the equivalent of around 2.9 ppm FC (it's 7 ppm FC in 350 gallons) to oxidize bather waste IF there is no ozonator (do you have an ozonator -- I don't recall you saying). So that translates into adding 1.8 ppm CYA for every person-hour of soaking. So if you don't soak that much, it won't climb very fast. Also, CYA will drop at around 5 ppm per month.

If you don't add CYA initially or more quickly then the downside is that the chlorine will be too strong. It will outgas more quickly so will appear to get used up faster beyond your bather load (i.e. in between soaks). It will oxidize skin, swimsuits and hair more quickly. Basically, it will be more like a commercial/public spa though as soon as some CYA builds up it will lessen the degree of chlorine's strength. So it's up to you whether you want to deal with this or not -- it's your spa and you can just see how it goes. The point is that you have the knowledge to deal with what is going on.

 

[norwood451]

Yep, now it is just me an my wife, and we only use it a few times a month. I spend more time cleaning and adding chemicals then I use it. It may be as big as 1000 gals. No ozonator, that would be cool. . I have asked before in this thread, but have not received an answer, so I kind of gave up on knowing.

However, since you brought it up again, do you think I should buy and liquid or powered CYM to get the levels up to 30ppm+? If so, what would you recommend that would be less costly? Also, if so, what target CYM should I increase to. As, a mentioned, my CYM levels are clearly under 30ppm.

 

[norwood451]

This is a follow up the issue I was having in March where the TC was extremely high compared to my experience with other chlorine tablets. I now know what the problem is now, which is that the Chlorine tables are defective or poor quality. I was using a higher quality tablet From January to May, but when I ran out of that brand, I started to use an economy brand distributed by In the Swim, "Econo-Chlor 3 Inch Pool Chlorine Tablets - 40 lbs. The price was a bit lower than its counterpart, and thought nothing about buying it. However, as you can see in the thread, it produced extremely high Total Chlorine reading (TC), and the only solution I could think of was to use less broken pieces of the tablets.

It has been four months since I started the thread in May, and Last week (June 28) I drained to spa because the CYA levels went were over 100 and the spa was impossible to balance and was accumulating green algae on the bottom of the spa. When I swept the bottom it would, of course, turn green, and it would filter out. I opened the filter and it was filled with green water. The spa was not green anymore, but was not clear. I did this a couple of times until I gave up and drained the spa.

The Econo-Chlor web page was taken down and the product was not being sold anymore. I contacted the seller and asked to return the product and surprisingly did not get any argument and was sent a return shipping label.

Needless to say, I would not use economy chlorine tablets again. At this point, I am reluctant to use any chlorine tablets. My current thought is not to use any CYA, as I cannot afford to drain my spa every 6 months. My other thought is to only use chlorine and add CYA separately.

I guess I need to read the pool school method again to figure the best way to sanitize my in ground, glass tile, outdoor spa. I am also open to suggestions, as I do not think there are many people with glass tile outdoor, in ground spas with waterfalls in CA.

 

[chem geek]

Needless to say, I would not use economy chlorine tablets again. At this point, I am reluctant to use any chlorine tablets. My current thought is not to use any CYA, as I cannot afford to drain my spa every 6 months. My other thought is to only use chlorine and add CYA separately.

I guess I need to read the pool school method again to figure the best way to sanitize my in ground, glass tile, outdoor spa. I am also open to suggestions, as I do not think there are many people with glass tile outdoor, in ground spas with waterfalls in CA.

Sorry to not respond earlier -- I only just saw this post.

You can look at the Pool School article from the Further Reading link called Using Chlorine in a Spa. Though you could try and add pure CYA separately, it's usually easier just to start out using Dichlor until you build up to 30-40 pm CYA and then switch to using bleach. Before you switch to bleach you'll want to lower your TA level to around 50 ppm and you'll want to add 50 ppm borates (usually with boric acid). This is the "Dichlor-then-bleach" method. You would use Dichlor for about one day per month since the CYA does slowly get oxidized by chlorine.

The main downside with the method is that you have to add chlorine every day or two, especially if you have an ozonator. Without an ozonator, you can probably get by adding chlorine twice a week if the spa is covered.

 

[norwood451]

Thank you for your response, and no hurry -- spa is drained due to drought, will be filled in January.

I looked link you sent and did some research on "Dichor" Which begs the question on what is the best Dichor to buy. I looked on Amazon and found several, at different prices, I am guessing that a chemical is a chemical, but due to my experience with tablets of chlorine, that logic is risky.

So, my first questions is what Dichor should I buy or does it matter and get the lowest cost? About how much do you think I will need for 800 gal?

Instant Conditioner (Natural) - What do you think of this product as an alternative to CYA and can be found at a low cost?
http://www.saveonpoolsupplies.com/s...1SOPSSP&e7=Y&e8=Y5976&pcode=115&keyword=Y5976

I understand the need to add Cyanuric Acid (CYA), but I still do not understand the advantage to Dichor over adding CYA, You said it is easier. When you think about it, adding the correct amount of liquid CYA and forgetting about it seems easier, but I am certainly not an expert.

So the next questions is why is Dichor better than or easier than straight CYA?

The link you included from Nitro indicated the need for Borates and he suggests a product called Gentle Spa, which certainly makes it easy use, but it is expensive. Also, Nito said you should “buffer you pH.”

What does it mean to “buffer you pH?” and since I do not know what that means, why do I have to buffer my pH?

Do you use borates if pH balancing is a problem or no matter what?

If I need to buffer my pH is it worth the extra cost to use Gentle Spa, or would it be just as effective using 20 MT Borax and muriatic acid?

INFO:
California
800 gal glass tile spa not covered
Not using an ozonator


David

 

[chem geek]

It's mostly that pure CYA doesn't dissolve quickly and you are adding so little to your spa that the traditional method of putting it into a sock either in front of a return or in the skimmer needs a slightly modified approach. At least your spa is a bit larger so 35 ppm CYA in 800 gallons would be 3.7 ounces weight or 3.9 fluid ounces volume (about 1/2 cup). So if you want to put this into a thin sock or panty hose or T-shirt and expose it to water flow to dissolve it, then that will work. For those with a 300 or so gallon spa that's only 3/16 cup of pure CYA.

Pure CYA is the least expensive approach while Dichlor is next because it also add chlorine you need while the Instant Pool Water Conditioner is the most expensive. See the prices below using the smallest containers (so you can get lower prices buying larger containers):

Product ... Amount ... Cost
Pure ........ 3.7 oz. ... $0.90
Dichlor ..... 7.4 oz. ... $3.21 but 38.4 ppm FC (45.5 fl.oz. 8.25% bleach) is around $0.80 or so, so net $2.40
Instant .. 11.2 fl.oz. . $2.69

I wouldn't use Gentle Spa. It's not completely pH neutral and it's expensive. I'd use granular boric acid you can get at Duda Diesel, The Chemistry Store, or AAA Chemicals. When Nitro says you need to buffer your pH he means that when you lower the Total Alkalinity (TA) to 50 ppm you are lowering the amount of bicarbonate pH buffer in the water that would resist changes in pH. The problem with the bicarbonate buffer is that it is also a SOURCE of rising pH due to carbon dioxide outgassing. Using boric acid provides additional pH buffering, so resistance to changes in pH, but without being a source of pH change itself.

If you prefer to use 20 Mule Team Borax and Muriatic Acid instead of the boric acid, that's up to you, but the boric acid is reasonably priced and easier to dose without the pH swinging up and down from adding Borax then acid (even split into alternating doses).

 

[norwood451]

Very helpful indeed, thank you.

As far as the liquid conditioner, I am not sure of the downside of using it, as a ½ gallon is only $19.50 with shipping and I can only find CYA liquid for about $18.00 for 16 oz. Also, I have only found Dichlor for just under $20.00 as well. So, no matter what I do, it appears I will be spending about $20.00.

Is cost the only reason to decide which is the best stabilizer to use? If so, do you have good source for CYA liquid?

The Duda Diesel recommendation is great! I did not know there was another option in regards to borates, as most of the forums I read referred to 20 MT borax.

Will I need more than one pound for 800 gallons? I think I need one pound per 1,000 gallons.

 

[chem geek]

Yes, cost is really the only issue with the liquid CYA. It's advantage is that it mixes quickly into the water. It's a slurry of sodium cyanurate so is fairly pH neutral and dissolves fairly quickly like a salt.

As for pure CYA (which is granular, not a liquid), you can get GLB Stabilizer in the 1.75 pound container for $6.83 (plus shipping) from poolgeek.com.

 

[norwood451]

Do you have a good source and recommendation for liquid CYA?

Do you know if you can use the Rainbow Cyanuric acid test kit 79 reagent as an additive as CYA to spa?

Is it okay to dissolve granular CYA in water before adding to spa?
http://www.ebay.com/itm/Pool-Chlori...708?pt=LH_DefaultDomain_0&hash=item3ce3f8bf5c

Below shows the ingreatents in the Material Safety Guide.
http://www.poolwater.com/msds/all/Pentair_Cyanuric_Acid_Solution_79.pdf

SOLUTION CYANURIC ACID 32 OZ
http://www.amazon.com/gp/product/B00DP5TPG2/ref=ox_sc_sfl_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

 

[chem geek]

There is only one liquid CYA and that is what you found, Natural Chemistry® Instant Pool Water Conditioner. In addition to being available at the source you found, it is also available at poolgeek.com in both gallon and 1/2 gallon sizes and a Google search will turn up additional sources for it as well.

Though you might be able to use the Rainbow Cyanuric Acid Test Kit 79, if you haven't obtained a test kit yet you should instead get the TFTestkits TF-100 that contains ample CYA tests based on Taylor chemistry. It looks like the Rainbow kit uses Pentair chemistry from the MSDS but shows refills using Taylor chemistry. However, the Rainbow has a different type of slider-based reader compared to the Taylor tube. We have no experience with this to know if it's as accurate or reliable as the Taylor tube used in the TF-100 (and Taylor K-2006).

You won't be able to dissolve much granular CYA in a smaller volume of water. It has a maximum solubility of 1500-2700 ppm so given your 850 gallons and a 35 ppm CYA target you'd have to dissolve the CYA in at least 11 gallons otherwise it may not all dissolve (it might take less dissolving it in buffered water). This is why we recommend putting CYA in a sock and hanging it over a return flow or in the skimmer.

 

[norwood451]

Thank so much for taking the time to answer all of my questions. I now know exactly what I will do in January after the drought.

As you pointed out for CYA, price is the main issue, but in my case the price will be $20.00 no matter what I buy. I found the Natural Pool water conditioner for under $20.00 on ebay and I only need to use a small about of the ½ gal, which will give me more than I need now and when I need to add more in the future or if I drain the spa again.

I am so glad you mentioned granular boric acid, as it seems so much easier compared to what I read about 20 M Team Borax.

Of course, will also be using liquid chlorine or bleach and between the three chemicals, I am sure I will avoid the issues I had in the last 6 months using economy chlorine tablets. If fact I will never buy chlorine tablets again.