Living with high CYA

FloridaPoolGal

LifeTime Supporter
Jan 8, 2016
113
Altamonte Springs, FL
Pool Size
20000
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I helped my neighbor through a SLAM a couple of years ago. I tried to talk her into using TFP but she declined and went back to pucks. She asked for my help again recently because, of course, she was fighting an algae outbreak...one she couldn't beat. Now, unfortunately, her CYA is up to 110 (at least that was my estimate using the CYA test.) She didn't want to change water out prior to doing the SLAM so I conducted it at the elevated CYA level. It took four days but there was no drop in the chlorine level last night and no CC so the SLAM is completed.

Other than having to conduct a SLAM at a high chlorine level, are there negative effects of living with a high CYA level? She will change out the water over time and she will be using TFP philosophy (with my help) so her CYA will be declining and no longer growing. She has purchased a TF-100 test kit and I will help her do her tests.

And, yes, she remembered when I told her she would be stuck with high CYA and fighting a continual battle with algae! :)
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,408
Laughlin, NV
Pool Size
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Fiberglass
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Pentair Intellichlor IC-40
Biggest issue is if your target range FC is above 10 ppm, you cannot accurately measure your pH. Also, IF, copper has been added to the water, you can create copper cyanurate. It shows up as purple stains on the pool surface.
 

markayash

Gold Supporter
Mar 21, 2016
2,903
Atlanta Ga
Biggest draw back I had was first you have to keep FC way up there which using pucks raises CYA more. Second issue was when I got an outbreak it took a LOT of chlorine. I felt strange buying 8 gallons of Liquid Chlorine at once and having to go back the next day and get more :)
 

FloridaPoolGal

LifeTime Supporter
Jan 8, 2016
113
Altamonte Springs, FL
Pool Size
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Biggest issue is if your target range FC is above 10 ppm, you cannot accurately measure your pH. Also, IF, copper has been added to the water, you can create copper cyanurate. It shows up as purple stains on the pool surface.

No copper ever added to my knowledge and there are no stains on the pool surface.

I was wondering at what chlorine levels the issues with being able to accurately measure pH started. I'm guessing diluting a sample doesn't work like it does for other thests.
 

FloridaPoolGal

LifeTime Supporter
Jan 8, 2016
113
Altamonte Springs, FL
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
Biggest draw back I had was first you have to keep FC way up there which using pucks raises CYA more. Second issue was when I got an outbreak it took a LOT of chlorine. I felt strange buying 8 gallons of Liquid Chlorine at once and having to go back the next day and get more :)
It's funny you say that because it crossed my mind. I sent her to refill the 2.5 gallon jugs at the pool store. I never priced bulk chlorine because I don't want to deal with the transporting the jugs. The chlorine in gallon jugs from Home Depot and Lowes has gotten more expensive during the pandemic to where it is about twice the price of the bulk chlorine. Luckily, my neighbor's pool is only 13,000 gallons.
 
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Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
1,833
Rancho Cucamonga, CA
You probably need to get a better estimate of the current CYA level by doing a diluted test. Dilute the pool sample with 50% tap water and do the test as usual. Double the test results for a more accurate reading.

Assuming current CYA is the 110 range and she stops using pucks, she might have a chance if she works on reducing the current CYA level over time. She'll need to test pH when FC drops below 10, then dose back up to target level per the CYA/Chlorine Chart.
 

FloridaPoolGal

LifeTime Supporter
Jan 8, 2016
113
Altamonte Springs, FL
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
You probably need to get a better estimate of the current CYA level by doing a diluted test. Dilute the pool sample with 50% tap water and do the test as usual. Double the test results for a more accurate reading.

Assuming current CYA is the 110 range and she stops using pucks, she might have a chance if she works on reducing the current CYA level over time. She'll need to test pH when FC drops below 10, then dose back up to target level per the CYA/Chlorine Chart.
Yes, I forgot about doing this and should get it done soon.
 

Katodude

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Aug 22, 2017
1,274
West Palm Beach/Florida
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You may want her to buy a digital pH meter to measure pH. They are not affected by high FC levels. You will have to calibrate them often in order for them to be accurate.

We are in the tail end of the rainy season, but you might want to consider draining to the bottom of the skimmer right before a big rain. Over time use rain to slowly replace the water. When the pool gets hot again in the summer the CYA will also start to degrade slowly.
 
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FloridaPoolGal

LifeTime Supporter
Jan 8, 2016
113
Altamonte Springs, FL
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
You probably need to get a better estimate of the current CYA level by doing a diluted test. Dilute the pool sample with 50% tap water and do the test as usual. Double the test results for a more accurate reading.

Assuming current CYA is the 110 range and she stops using pucks, she might have a chance if she works on reducing the current CYA level over time. She'll need to test pH when FC drops below 10, then dose back up to target level per the CYA/Chlorine Chart.

I diluted and retested and my estimate of 110 was good.
 

FloridaPoolGal

LifeTime Supporter
Jan 8, 2016
113
Altamonte Springs, FL
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
You may want her to buy a digital pH meter to measure pH. They are not affected by high FC levels. You will have to calibrate them often in order for them to be accurate.

We are in the tail end of the rainy season, but you might want to consider draining to the bottom of the skimmer right before a big rain. Over time use rain to slowly replace the water. When the pool gets hot again in the summer the CYA will also start to degrade slowly.

Thank you for reminding me about digital pH meters. I actually had a new one (replacement for one that went wacko) sitting in my pool box I had not yet calibrated. I calibrated it and measured her pH at 7.5. That was a couple of days ago so it is time to measure again. I'm guess it's up a bit.
 

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FloridaPoolGal

LifeTime Supporter
Jan 8, 2016
113
Altamonte Springs, FL
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
Are CH and TA tests accurate at very high chlorine levels? I measured CH and TA prior to the SLAM. CH prior to SLAM was 300 and after was 275. That's only one drop difference so basically the same. TA prior to the SLAM was 50 and 90 after but I had added baking soda prior to the SLAM and after the SLAM because the pH was quite low. My neighbor jumped the gun with adding the container of chlorine before I had optimized the pH and I used baking soda because it was handy.

After the SLAM, I got the TA I expected based on the amount of baking soda I had added (thank you Pool Math app). The color change during the TA test was a different color but there was an obvious change.

Is the pool swimmable at the high chlorine level or does it need to let it drop a bit before use? Last measurement was about 30. I will measure again today. The pool water looks great. Very clear and sparkly!
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
8,624
Central California
Pool Size
12300
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Wow, you are one good neighbor! She resists TFP guidelines and instructions, and you get stuck with the work and figuring out work-arounds for her resistance. You have more patience than I do. Bless your heart. 👏

I would have pushed to do a partial drain and get the CYA down to a manageable, and measurable, level, and be done with it. Then you both could make better sense out of test results and she could enjoy a TFP pool and less chlorine lugging.

Technically, it's safe to swim in elevated FC up to SLAM level. But with an iffy CYA number it's tough to say what that SLAM-level FC actually is (another reason to bring down the CYA)...
 

FloridaPoolGal

LifeTime Supporter
Jan 8, 2016
113
Altamonte Springs, FL
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
Wow, you are one good neighbor! She resists TFP guidelines and instructions, and you get stuck with the work and figuring out work-arounds for her resistance. You have more patience than I do. Bless your heart. 👏

I would have pushed to do a partial drain and get the CYA down to a manageable, and measurable, level, and be done with it. Then you both could make better sense out of test results and she could enjoy a TFP pool and less chlorine lugging.

Technically, it's safe to swim in elevated FC up to SLAM level. But with an iffy CYA number it's tough to say what that SLAM-level FC actually is (another reason to bring down the CYA)...

My neighbors are an adult daughter (still working) and her mother (retired). The mom has just been diagnosed with a tumor on her kidney which is almost certainly cancerous because she is a longtime smoker. It's small and was found accidentally. I took her to the kidney surgeon yesterday and he was fine with her getting another scan in December to see if anything has changed. He operates using the DaVinci robot and is the 'go to' guy in the area so she also lucked out there. Oh, and mom stepped on the gas instead of the brake the other day and ran the car into the front of the house. She's fine. The house is mostly fine. The car sustained some damage. Quick and easy conversation about mom giving up her keys! There is a lot of drama over there right now so I'll cut them some slack with respect to not doing a water change right away.
 
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