Any reason not to add extra chlorine to last more days?

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pcm2a

pcm2a

0
Aug 25, 2017
260
Mt Juliet, Tn
My pool guy used the tablet method that kept my pool crystal perfect all summer but as a side effect gave me a sky high CYA. Going into this summer I decided to try out the recommended way. The thing is I've only been taking these daily or every other day readings for a couple weeks and I can already say "I'm way too lazy for this". With that in mind before abandoning the effort before it even has a chance I had two different questions.

It's not warm enough to swim yet but it's getting warm during the day. I'm losing from 1-2 FC a day. My CYA is around 80 giving me a minimum of 6, 9-11 preferred, shock 31. Is there any difference between adding some bleach every day to keep the level at 11 vs raising it up to say 20 and checking it again in a week? Would this also be safe to do during the swimming season since the shock is 31?

Second question is testing for FC. Is there any method of testing besides DPD that will show a FC or TC with a value of 10 or higher? I watch my pool guy use his kit to test the water, takes 3 seconds. His kit does not show a TC value that high. I'm in here scooping out powder, slowly adding in drops....yeah I'm lazy.

If I average 4 tablets a week for the 6 month swim time, that is approximately +230 FC added and just over one $90 bucket of tablets. Pool math tells me I will need 45 gallons of 10% bleach, at Walmart's price ($3.67 plus tax ~$4) that will be about $180.
 
Nice to meet you via TFP :)

Totally up to you for sure, and here's a few comments.

Keep testing frequently until you get a good feel for it, but you don't need to test every day after you know your trends. After a while, you add the daily amount of bleach knowing how much it tends to be, based on tests twice a week or every other day, whatever works for you.

If you add more chlorine to get through extra days, totally fine but you lose more to sunlight. Say it's 1/4 lost per day. Start with 8, you lose 2/day. When you start with 32 under the same conditions, you'll lose around 8/day the first day, then 6, then 4.5, then 3.5, then 2.5, and then time to add chlorine again. You used about 5 ppm/day instead of 3. It works, but costs more.

An SWCG or liquid chlorine injector pump can take away the effort of adding chlorine, and an SWCG also makes it for you.

You might be able to find 12.5% chlorine, which reduces the hauling by 20%, and hopefully you can find a better price than that.

Pucks are fine, just watch your CYA, stick to the [FC/CYA][/FC/CYA], and raise your pH when need be. You can drain 1/3 of the pool when you get to 90 ppm CYA. Based on your 1.6 ppm/day chlorine loss, and starting from 80 ppm CYA, you'll drain 1/3 six times in six months to stay between 60 and 90 ppm CYA. It's fair to include pH raising and water cost in the estimate, and water replacement gets offset to a varying degree by rain leading to overflow, splashout and backwashing.
 
As was pointed out, you'll be wasting more chlorine that way as higher concentrations of FC have greater rates of loss at a fixed CYA.

You're basically asking if it's alright to use the "pool service tech" method of pool care. You can certainly do whatever you like with your pool but no one here will endorse that method. In its most basic sense, the pool guy method (let's call it PGM for short) is based on getting the pool water chemistry "good enough" so that he only has to visit, at most, once every 7 days. So, in a PGM managed pool, you jack up the CYA to 100-120ppm and then you dose the pool with 15-20ppm FC. The test kit your PGM guy is using is likely the basic yellow OTO chlorine test that reads TC only on one side and pH on the other. The tech simply starts his visit by checking TC and making sure the OTO has some faint yellow to it. That tells him there's about 1ppm or so FC in the water. He then dumps in enough liquid chlorine or dichlor powder to get that FC up to 15-20ppm but doesn't really bother to check since his OTO drops will just turn burnt-orange/brown from the high chlorine. His next step is to ensure that the blue chemical floater, or in-line chlorinator or skimmer basket has a bunch of trichlor pucks in it as that is going to be your continuous FC source. After that, he might be diligent and check pH and TA (almost always using test strips) but he likely won't. If he does test for pH and see's the strips say "LOW", he'll dump a bunch of soda ash in the water and call it a day. Whether or not he vacuums depends on the contract.

In the PGM pool, chemical levels are "out-of-whack" all the time - either you have way too much FC in the water (to the point of being uncomfortable to swim in and smelly) or you have too little FC (to the point of being dangerous to swim in). The pH is all over the place but that's not too noticeable as it takes very large pH excursions to cause bather discomfort but your equipment certainly doesn't appreciate it). So, in the end, your water may be clear but it's definitely not safe (but how would you know that since most pool owners never check anyway and just trust the PGM to do it's magic??).

If you add 230ppm FC all season using trichlor (and you'll likely add more than that) then your CYA will go up by 140ppm. So if you start the summer at 60ppm CYA, you will be up to 200ppm by the end of the season and you'll need to drain 70% of your pool water to restore your CYA back to 60ppm. That's about 14,000 gallons of water. Rain water overflow might help reduce that a but, but we're talking less than 10% at best. So yes, you can use trichlor tablets but you'd better keep an eye on the CYA or else your water will become very reactive to algae.

No, there is no other test kit. The DPD-FAS test is the absolute most accurate residential pool test there is. If you wanted to make testing a little easier, you could go buy a LaMotte ColorQ to do all the readings but those cost hundreds of dollars and they need to be recalibrated often.

I had a buddy that I worked with who had his own unique method of car care - he never changed the oil. All he did was check the dipstick now and then and add a quart of oil when it showed a little low. That's it. He never opened the drain plug or changed the filter (unless it was leaking or his oil light came on) or took the car to JiffyLube. He couldn't be bothered and he was too cheap to spend the money on routine service. Was his method super-easy? Sure. Did his method prematurely wreck his car's engine? Most definitely. Did he save money? Probably not when you take into account the damage done. But, at the end of the day, it was his car and his time and his money and I wasn't about to change his mind.

Let us know what you decide to do and keep asking questions. We're happy to help....
 
needsajet said:
If you add more chlorine to get through extra days, totally fine but you lose more to sunlight. Say it's 1/4 lost per day. Start with 8, you lose 2/day. When you start with 32 under the same conditions, you'll lose around 8/day the first day, then 6, then 4.5, then 3.5, then 2.5, and then time to add chlorine again. You used about 5 ppm/day instead of 3. It works, but costs more.
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Thanks! This was the item I was missing, losing a percentage of chlorine a day and not a somewhat fixed amount. Now I get why you would want a lower CYA. If I'm losing 1/4 at 11 (2.75) then I would only lose 1.5 if I could keep my FC around 6. That would cut my guestimates by over half making the bleach cost less than even the tablets.


needsajet said:
Pucks are fine, just watch your CYA, stick to the [FC/CYA][/FC/CYA], and raise your pH when need be. You can drain 1/3 of the pool when you get to 90 ppm CYA. Based on your 1.6 ppm/day chlorine loss, and starting from 80 ppm CYA, you'll drain 1/3 six times in six months to stay between 60 and 90 ppm CYA. It's fair to include pH raising and water cost in the estimate, and water replacement gets offset to a varying degree by rain leading to overflow, splashout and backwashing.
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The only other chemical besides pucks used last season was baking soda a few times, which cost very little. Pool was drained zero times and ended up with a CYA in a range of 120-130. It's down around 80 now with just rain/backwashing. With the amount of water needed to be added due to evaporation once summer gets here I do not plan on any draining. But you are correct if I did have to drain 1/3 would be about $60 in water bill costs.
 
JoyfulNoise said:
If you add 230ppm FC all season using trichlor (and you'll likely add more than that) then your CYA will go up by 140ppm. So if you start the summer at 60ppm CYA, you will be up to 200ppm by the end of the season and you'll need to drain 70% of your pool water to restore your CYA back to 60ppm. That's about 14,000 gallons of water. Rain water overflow might help reduce that a but, but we're talking less than 10% at best. So yes, you can use trichlor tablets but you'd better keep an eye on the CYA or else your water will become very reactive to algae.
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Pool was never drained and at the end of the season it was around 120-130. Backwashing weekly or bi-weekly drained at least an inch out and I had to add at least 1-2 inches a week in the July-September range due to evaporation and pool usage. Maybe that was enough to keep it high but not 200ppm high. I'm hoping that also brings me down pretty quick from the current 80 to a better range.
 
Happy to help

Just to clarify, evaporation doesn't take CYA with it - only the water goes.

Weekly or bi-weekly backwashing would definitely be removing CYA, but that sounds like an opportunity to save money. Backwashing once a month or less is more the norm. Many people here backwash a few times a year, some once or twice per year.

The ~1/4 loss per day is the sunlight loss (early season/late season) with no contamination to neutralize. It rises and falls depending on how high the sun is in the sky, the CYA level, and other factors. I just explained that way to illustrate. Your daily loss of FC will also vary depending on use of the pool, incoming or nascent organics, etc. On average, it's 2 to 4 ppm FC per day, but you'll also hear of less than 1 (light use, covered, always clean) and 5 or more (small volume, heavy use, pets swimming).
 
You can certainly manage a pool with trichlor pucks if you want that to be your primary FC source. The biggest issue with that is you need to constantly adjust the FC upwards as the CYA rises. So that means you need to test CYA on a regular basis (probably twice per month) and then adjust your FC target accordingly to maintain a 7.5% FC/CYA ratio. In the TFP method you hold the CYA constant and you add chlorine everyday to reach a specific target FC.

In your pool, the CYA level is going to vary a bit because of rain and backwashing (unlike my pool where CYA almost never changes) and the test for CYA is the hardest test to do in the kit. Also, trichlor is acidic and so you really ought to do the TA frequently to make sure the trichlor isn't eating up all your TA. That makes using trichlor pucks a bit trickier.

How did your former pool guy do it so easily? He essentially ignored the CYA and TA for the most part. You can certainly do that as well but then you'll be constantly reacting to problems rather than preventing them in the first place. As the old saying goes - "An ounce of prevention is worth a pound of cure..."
 
needsajet said:
Just to clarify, evaporation doesn't take CYA with it - only the water goes.
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That is interesting. So only backwashing over the past few months has lowered my CYA from 120+ to 80. I'm glad it raining outside right now, smells like money.

needsajet said:
Weekly or bi-weekly backwashing would definitely be removing CYA, but that sounds like an opportunity to save money. Backwashing once a month or less is more the norm. Many people here backwash a few times a year, some once or twice per year.
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Thanks, I will keep that in mind. I have backwashed quite a few times because my pool was full all the way to the top from rain.

needsajet said:
Your daily loss of FC will also vary depending on use of the pool, incoming or nascent organics, etc. On average, it's 2 to 4 ppm FC per day, but you'll also hear of less than 1 (light use, covered, always clean) and 5 or more (small volume, heavy use, pets swimming).
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No matter how I add up the pool math, 2-4 would be costly in bleach, 4 would be real costly. 2 FC = 51oz of 10% bleach for ~180 days is 9180oz at $4 per 128oz = $286.

With everything I have learned so far I am baffled at how my pool stayed crystal clear with only 4 tablets a week and a couple times with baking soda. Luck or magic maybe.

borjis said:
It occurred to me you could have the best of TFP methods AND less work all in one, if you added an SWG to your pool.
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If it is electronic it breaks. Already had to repair too many things. The last thing I'll be doing is adding another expensive electronic item to break on me. If they were cheap I'd be all over it. As it goes I'm waiting for this old Aqualogic System to go out on me. I had to watch on ebay just to get a remote controller for it.
 

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JoyfulNoise said:
How did your former pool guy do it so easily? He essentially ignored the CYA and TA for the most part. You can certainly do that as well but then you'll be constantly reacting to problems rather than preventing them in the first place.
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He checked chlorine weekly using a drop method (not DPD) which I assume is showing TC. Fill the tube, few drops, done. He for sure was not using the CYA chart and like the pool stores just wanted to keep the chlorine in a 2-4 range. He threw in the 4 tablets into the skimmer, they dissolved over the course of the week. Baking soda only happened every month or so, so I'm guessing a monthly pH check there. No CYA checks ever.

How could he have kept my pool algae free with a sky high CYA and 4 tablets a week? Seems like the FC would always have been below the CYA chart limit.
 
Low FC use can be a bunch of things - low use, low organic load, low pee, and a dozen other possibilities. The high CYA would cut the FC depletion down as well. But one to worry about is low pH. Low pH makes the chlorine stronger and makes it last longer, but is corrosive to plaster and equipment, and also uncomfortable on the eyeballs. I mention it because you mentioned baking soda being added, which doesn't raise pH much, but will hasten pH rise later. He should have been adding soda ash or borax to raise pH, as well as baking soda to keep the TA up to a correct level.
 
needsajet said:
Low FC use can be a bunch of things - low use, low organic load, low pee, and a dozen other possibilities. The high CYA would cut the FC depletion down as well. But one to worry about is low pH. Low pH makes the chlorine stronger and makes it last longer, but is corrosive to plaster and equipment, and also uncomfortable on the eyeballs. I mention it because you mentioned baking soda being added, which doesn't raise pH much, but will hasten pH rise later. He should have been adding soda ash or borax to raise pH, as well as baking soda to keep the TA up to a correct level.
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I can't say what he was testing but you would assume it had a low TA so he added the baking soda. I just assume he did more testing monthly than weekly. My son and I swam in it almost daily and I never had any eye burning.

You said baking soda doesn't raise pH until later, what's the definition of later? I took a pH reading of 7.6, added 12 pounds of baking soda to raise TA and two days later my pH was 8.0. I added muratic acid to bring it back down to 7.6 last Saturday. Haven't taken another TA reading yet.

cfherrman said:
A trouble free pool, priceless
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I had a trouble free pool last summer when ignorance was bliss. Oh and the cost of a pool guy is greater than any possible calculation I could come up with. Drain and refill the pool monthly might be about the same cost.
 
There's better people than me to explain, but in the absence of a chemical addition, pH rises due to out-gassing of carbon dioxide as the pool water tries to achieve equilibrium with the atmosphere. The purpose in the pool for having TA at all, is to buffer the water against pH drop. When there is more TA than needed to balance pH, it puts upward pressure on pH, causing the pH to rise faster and to a higher number. A few days to respond to an excessive TA addition is normal. If it got a lot of swimming, waterfalls, slides and the like, the surface area of the water increases and it could happen more quickly.

That 12 lbs of baking soda would raise your TA by about 40 ppm. Getting rid of it will take around the same amount of 32% muriatic acid, but use PoolMath after you get your TA reading. Don't do the acid all at once, because it will lower your pH way too much. You need to do that part in steps. Many pools will settle somewhere between 40 and 60 ppm TA when pH is kept around 7.6 to 7.8, but TA coming in with the top-up water causes TA to climb over time, needing acid to offset. If you switch to TFPC, there's every chance you will never (or at least very, very seldom) need to add TA.

What you're describing is called the TA-Acid Roller Coaster around here. PoolChemCo says you need 80-120 ppm TA (or even higher), so you buy "Alkalinity Up" (aka buffer, aka baking soda). Then your pH rises faster, so you buy acid, which eliminates some of the TA. Back to the shop for Alkalinity Up, etc., and within a couple weeks you don't need the GPS any more.
 
I added muratic acid using the pool calculator to bring my pH from 8.0 to 7.6, 21oz, all at once. The day after I took a reading and it was 7.6. Been two days since then and I haven't taken another reading yet to see if the pH has increased more.
 
CYA is 80

3/2/18
pH: 8.0
TA: 110
Added 21oz muratic acid

3/3/18
FC: 9
ph: 7.6

3/4/18
FC: 7.5
Added 128oz 10% + 96oz ~1-2% dollartree garbage
(Added more bleach than needed and made this thread)

3/5/18
FC: 13
pH: 7.8
TA: 110

Looks like I should add a bit more muratic acid tomorrow to keep dropping it to 7.6 until it sticks? I'm looking forward to tracking the FC over the next few days and see what the percentage lost is.
 
If you do a full list, we can help better. Here's the common format that makes pool numbers easily read by everyone here:
FC 13.0
CC x.x
pH 7.8
TA 110 (last weekly)
CH xx (last monthly)
CYA 80 (last monthly)
Temp xx

This is a concrete and plaster pool right? You're actually fine at 7.8 (unless your CH is really high), and you can add acid when it gets above 7.8

As far as lowering TA, you can do it slow, medium or fast, but it will happen either way from your future acid additions. If you find pH adjustments are too frequent for your liking, then lower TA more quickly. For me, once a week is no big deal and that works for me at TA 70, but every pool has it's own ideal combo depending on use and owner.

To lower it slow, correct to pH 7.5 each time it goes over 7.8
To lower it medium fast, correct to pH 7.0 each time it goes over 7.8
To lower it fast, you can do it aggressively with this method: Pool School - Lower Total Alkalinity

Either way, it will take the same total quantity of acid to remove total alkalinity
 

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