88 CYA and chlorine only lasts 2 days…

AJ81

Well-known member
Aug 31, 2023
77
Dallas, TX
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
We got a new pool and it was up and running for Memorial Day. Our pool project manager taught us the basics which really screwed us up. He told us to load the chlorinator with do dichlor tabs. (Do they make tabs without CYA?) During the early days he came over often and checked levels and chlorine was always 0 so he’d load the tabs up again and told us to do the same. In a few months we had CYA of 116! Chlorine dissipates in 3 days and drops to 0. Leslie’s pool told us to get the tabs out of the pool and use the granulated calcium hypochlorite 73% and to dump in 2 16oz bags every 3-4 days. Still chlorine is back to zero by day 4. A family member steered me to this website. In the meantime I’m dumping 1 1lb bag of the above mentioned chlorine ever other day until I figure out what to do. It’s also worth noting that despite our pool manager saying new pools require a lot of acid, our ph was 7.4 everyday for the first few months so we never added muriatic acid on a regular basis until about a month ago. He never told us a thing about CYA. Water is clear and I don’t see algae. I’m keeping the ph at 7.4-7.6 and alkalinity has been 80-100 all summer pretty much. How can I stop the chlorine from being depleted?
 
We got a new pool and it was up and running for Memorial Day. Our pool project manager taught us the basics which really screwed us up. He told us to load the chlorinator with do dichlor tabs. (Do they make tabs without CYA?) During the early days he came over often and checked levels and chlorine was always 0 so he’d load the tabs up again and told us to do the same. In a few months we had CYA of 116! Chlorine dissipates in 3 days and drops to 0. Leslie’s pool told us to get the tabs out of the pool and use the granulated calcium hypochlorite 73% and to dump in 2 16oz bags every 3-4 days. Still chlorine is back to zero by day 4. A family member steered me to this website. In the meantime I’m dumping 1 1lb bag of the above mentioned chlorine ever other day until I figure out what to do. It’s also worth noting that despite our pool manager saying new pools require a lot of acid, our ph was 7.4 everyday for the first few months so we never added muriatic acid on a regular basis until about a month ago. He never told us a thing about CYA. Water is clear and I don’t see algae. I’m keeping the ph at 7.4-7.6 and alkalinity has been 80-100 all summer pretty much. How can I stop the chlorine from being depleted?
Also, we just tested chlorine and it’s at 4. I put the pound of chlorine in Wednesday morning.
 
Also, we just tested chlorine and it’s at 4. I put the pound of chlorine in Wednesday morning.
Both your pool manager and Leslie’s are going to hurt you in the long run. You can use dichlor to chlorinate but CYA will build up over time and render it harder to keep the water sanitary. Calhypo will do the same things except calcium will build up and cause scaling. Both of those problems require replacing the water to get rid of either CYA or calcium.

What you can use to chlorinate is liquid chlorine (ie plain bleach), sometimes labeled chlorinating liquid at Walmart, Home Depot, etc.

The related issues is that Leslie’s and lots of pool contractors use really unreliable water testing equipment. So TFP would recommend you get one of only two test kits that are available online to test your own water and reply back with the results. The kits are usually only available online.

Until the test kit arrives, you can add 5ppm of liquid chlorine to your pool each day to keep it clean and keep the CYA and calcium from getting too high.

Here’s a link to the proper chlorine levels for pools:

If your water is still clear you may not be in trouble yet. But if you need it, here’s how to clear it up:
 
We do have the self kits and we test the water nearly everyday since day 1. I will test in a bit when the sun comes up and will report back today’s numbers. As of Wednesday I brought a ph down to 7.4 from 7.8 and the alkalinity was 100. Chlorine last evening was 4 so we will see if we’ve lost any overnight….
 
What type of test kit do you have? If it is something the builder provided, or you got from a local pool store, it likely does not cover everything needed including CYA and FC.

What we do have good locally is liquid chlorine. Not sure where you are in Dallas, but in the northern'burbs the best places are walmart (chlorinating liquid in white jugs with the pool/outdoor stuff) or pinch a penny pools.
 
I have the proper kits that everyone here recommends. My chlorine went from 4 to 2 overnight so according to this website I need it at least 7. My question is how do I determine how much liquid bleach to add? I used pool math and it says 208oz of 6 weight% bleach. What is 6 weight % bleach?
 
I have the proper kits that everyone here recommends. My chlorine went from 4 to 2 overnight so according to this website I need it at least 7. My question is how do I determine how much liquid bleach to add? I used pool math and it says 208oz of 6 weight% bleach. What is 6 weight % bleach?
So the TF-100?

As for the bleach, it should say on the bottle. Standard laundry bleach ranges from ~3% to 6% based on brand, age, etc. Liquid chlorine that you get from Walmart, Lowes, Home Depot, etc is usually 10%. Pinch a penny is usually 12%.
 
Once I dump in my two bottles of bleach, when is it safe to swim? I remember our pool manager saying any chlorine level over 5 is dangerous, but since our CYA is high that shouldn’t be the case here correct?? We checked CYA this morning and it’s between 70-90. The dot test is an imperfect test so hard to know the exact number. Leslie’s last said we were at 88 and that was 6 days ago.
 

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We do have the self kits and we test the water nearly everyday since day 1. I will test in a bit when the sun comes up and will report back today’s numbers. As of Wednesday I brought a ph down to 7.4 from 7.8 and the alkalinity was 100. Chlorine last evening was 4 so we will see if we’ve lost any overnight

How did you get the 88 for a CYA result? The kit only measures in increments of 10ppm. If you were just interpolating between lines, your CYA is always rounded up to the nearest 10ppm. So call it 90ppm. If that’s the case, your FC should never be allowed to drop below 6ppm, preferably keep it up near 9ppm

Edit: looks like we were replying at the same time. Just report numbers from either the TF-100 or the Taylor K2006 test kits. No one trusts Leslie’s test results or results from any other test kit.
 
That explains a lot. Every time we went to Leslie’s they said our alkalinity was 20-30 lower than what our kit consistently says. I kept asking them why that is and I received a lot of attitude. I’d say our CYA is 80 then.
 
That explains a lot. Every time we went to Leslie’s they said our alkalinity was 20-30 lower than what our kit consistently says. I kept asking them why that is and I received a lot of attitude. I’d say our CYA is 80 then.
They report adjusted alkalinity which tends to make them recommend you buying something to raise it. If you use liquid chlorine to sanitize the water, you can keep the TA around 50-60 which helps keep the pH more stable.
 
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Getting back to my initial question - why do I keep having to add chlorine every other day? How can I get it up and keep free chlorine at a stable level?
 
Getting back to my initial question - why do I keep having to add chlorine every other day? How can I get it up and keep free chlorine at a stable level?
Pools use about 3-5ppm of chlorine every day in the summer. Winter it drops down to less than that. No way around it. If it’s consuming more than that, you have some organic contamination (algae) which requires SLAM process to get rid of it. When your chlorine gets below the recommended FC/CYA ratio, the water becomes susceptible to algae.

Thats why lots of people switch to a salt water chlorinator. It adds chlorine every day automatically.
 
Since ours lost 2 ppm overnight (we did test this am before the pump turned on) don’t we need to slam? I’m hosting kids tomorrow to swim
 
Last edited:
Since ours lost 2 ppm overnight (we did test this am before the pump turned on) don’t we need to slam? I’m hosting kids tomorrow to swim.

Maybe. To confirm, you used the FAS-DPD test to measure the chlorine last night after dark and then measured it again this morning before the sun came up? I’d suggest posting all of your latest test results.
 
SLAM on. The kids can swim so long as you can see the bottom for swimmer safety / rescue (God forbid).

Our pool project manager taught us the basics which really screwed us up.
The industry recs to keep chlorine at 1-3 ppm are simply head scratching when the sun burns off up to 5ppm, daily, in sunny TX. They aren't telling you to start at 8 and end at 3. No sir. That would likely cover you most days this time of year. They're telling you that you can start at 1-3 (and then lose 5).
 

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