Cyanuric Acid High - Chlorine not holding

AKA

Member
May 29, 2018
5
Danville/ Ca
We have a pool service and they have been doing a terrible job. First we had metal stains all over the pool and it was finally removed with asorbic acid. Now we have high cyanuric acid of 210 and the pool doesn't hold chlorine and now starting to get green algae growth on sides of pool and in spa. I live in California and we are in a drought so I cannot drain part of the pool to lower the cyanuric acid levels. I ordered Bio Active from Amazon but it won't come for 10 days. Any suggestions on what I can do besides dumping in unstabilized chorine to stop the algae growth. I have a 20,000 gallon in ground pool and I put in 1.5 pounds of unstabilized chlorine shock at night to bring chlorine levels up to 1ppm but by the next day the chlorine and free chlorine are below 1ppm again. Should I keep trying to dump more unstabilized chlorine in the pool. Leslies recommended I only dump in 1.5 lbs at a time.
Free chlorine .07
Total chlorine .07
ph 7.2
Total alkalinity was 35 raised to 80
Calcium hardness 260
Cyanuric Acid 210
Iron 0
Copper .1
Phosphates 142
TDS 600
 

ajw22

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Jul 21, 2013
29,153
Northern NJ
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You need to lower your CYA level by 80% to 90%. Look into a Reverse Osmosis water treatment except that water needs to be algae free for RO.

Dumping in unstabilized chlorine at your CYA levels are drops in the ocean. You would need to get your FC level up over 80 ppm to deal with the algae. That is that is the chemistry and there are no shortcuts to it.

Those looks like pool store tests and we don't rust any of those values. Your CYA may be different. We recommend you do your own testing with a TF-100 Test Kit ™ or Taylor K-2006C. Following TFPC methods with your own test kit will keep you from getting into this situation again.
 
Last edited:

Bperry

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Aug 20, 2020
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Knoxville, TN
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We have a pool service and they have been doing a terrible job. First we had metal stains all over the pool and it was finally removed with asorbic acid. Now we have high cyanuric acid of 210 and the pool doesn't hold chlorine and now starting to get green algae growth on sides of pool and in spa. I live in California and we are in a drought so I cannot drain part of the pool to lower the cyanuric acid levels. I ordered Bio Active from Amazon but it won't come for 10 days. Any suggestions on what I can do besides dumping in unstabilized chorine to stop the algae growth. I have a 20,000 gallon in ground pool and I put in 1.5 pounds of unstabilized chlorine shock at night to bring chlorine levels up to 1ppm but by the next day the chlorine and free chlorine are below 1ppm again. Should I keep trying to dump more unstabilized chlorine in the pool. Leslies recommended I only dump in 1.5 lbs at a time.
Free chlorine .07
Total chlorine .07
ph 7.2
Total alkalinity was 35 raised to 80
Calcium hardness 260
Cyanuric Acid 210
Iron 0
Copper .1
Phosphates 142
TDS 600
The only unstabilized chlorine is sodium hypo/pool shock/bleach. You are probably adding cal-hypo if it’s a powder, and it adding calcium to the water.

You will have a hard time keeping algae at bay with 210 CYA. But if those values are from a pool store or test strips then there’s no way to know if the number is accurate or not. TFP recommends the Taylor K2006C (Amazon) or the TF-100 test kits.

All that said, the CYA reducers are known not to work or only work for a few people. I’d recommend exchanging the water out. Until then you’ll be needing to add a lot more than 1.5lbs of chlorine each day. If it’s already green, you’ll need close to a gallon of liquid each day.
 

ajw22

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TFP Guide
Jul 21, 2013
29,153
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
If it’s already green, you’ll need close to a gallon of liquid each day.

1 gallon of 10% liquid chlorine will raise his 20,000 gallon pool by 5 ppm. That will not make a dent in an algae situation with CYA over 200.

SLAM Process at CYA of 200 would be over 80 ppm and need over16 gallons of 10% liquid chlorine.
 
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Bperry

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Aug 20, 2020
1,021
Knoxville, TN
Pool Size
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1 gallon of 10% liquid chlorine will raise his 20,000 gallon pool by 5 ppm. That will not make a dent in an algae situation with CYA over 200.

SLAM Process at CYA of 200 would be over 80 ppm and need over16 gallons of 10% liquid chlorine.
Yea, that’s kinda what I meant. He needs a gallon of chlorine just to keep things where they’re at now. Getting rid of the algae is another issue. Exchanging the water (or I guess a reverse osmosis treatment) is really needed.
 

Bperry

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Aug 20, 2020
1,021
Knoxville, TN
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A gallon of LC will not keep his algae from growing.
But one of the standard advice from @mknauss is that you need to add 5ppm of chlorine each day (When accurate testing isn’t available) to keep things from getting worse until a proper test kit arrives. Am I misunderstanding something?
 

ajw22

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Jul 21, 2013
29,153
Northern NJ
Pool Size
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Salt Water Generator
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Pentair Intellichlor IC-60
But one of the standard advice from @mknauss is that you need to add 5ppm of chlorine each day (When accurate testing isn’t available) to keep things from getting worse until a proper test kit arrives. Am I misunderstanding something?

Most folks do not have CYA over 200. And that is a holding action for a few days while usually waiting for a test kit. It is a generic recommendation we use when the actual problem is unknown. It will kill some algae but things may still get worse. It is not a long term answer for a situation like this.
 

Hap

Member
Oct 14, 2014
5
Fort Worth TX
Question for the experts about AKA's problem. AKA is asking for "suggestions on what I can do besides dumping in unstabilized chorine to stop the algae growth," and I take that to mean *until* he gets his CYA under control. So, my question is, would it do AKA any good to add an emergency dose of Polyquat to hold the fort, so to speak, until he resolves the CYA problem?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,153
Northern NJ
Pool Size
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Plaster
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SWG Type
Pentair Intellichlor IC-60
So, my question is, would it do AKA any good to add an emergency dose of Polyquat to hold the fort, so to speak, until he resolves the CYA problem?

Algaecides only help prevent algae. Once you got it in the water they are of little value. Chlorine is the only thing that will eradicate the algae and keep it from multiplying.
 

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Bperry

Gold Supporter
Aug 20, 2020
1,021
Knoxville, TN
Pool Size
27000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60
Most folks do not have CYA over 200. And that is a holding action for a few days while usually waiting for a test kit. It is a generic recommendation we use when the actual problem is unknown. It will kill some algae but things may still get worse. It is not a long term answer for a situation like this.
Ok, I guess that makes sense but he’s still replying on pool store test for that CYA value (I assume). So would it be better to assume Leslies is correct about CYA and replace the water now or order a test kit and add chlorine until it arrives?
 

Rocket J Squirrel

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Jun 7, 2018
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Alamo, CA
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East Bay MUD is only at Stage 1 drought as of this date. You should be able to drain & refill without penalty if you do it soon before we enter higher drought stages. Make sure the drainage goes to the sanitary sewer, not to the storm overflow drains.

How sure are you of CYA 210? Have you been able to verify that from a source other than Leslie's?
 
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