Cyanuric Acid Level

[FresnoRick]

I have a problem with my cyanuric acid level being too high. I understand that ideal levels should be between 25 - 50 ppm. Upon opening my pool for the summer, I discovered with a test kit that the level of cyanuric acid (stabilizer) in my pool was 100ppm. I found out from local pool suppliers that the normal reason for this is that prolonged use of stabilized 3" tablets (which contain c.a.), will result in high levels of residual c.a., after the chlorine has dissapated. They also said the normal fix is to drain some? water out of the pool and refill with fresh water. I drained about 2' of water out of an 18' x 36' pool and then refilled. The level of c.a. was then 80ppm. Not wanting to drain all that water out again, I reasoned that if I now used non-stabilized liquid chlorine for a period of time, some more of the c a would be diluted as I refilled the pool from normal evaporation. It has been about a month now and the c a level has gone back up to 100!

Where did I go wrong? Does anybody have any experience with this? Please help. I'm losing my confidence in the local pool suppliers. Thank you.

[poollady]

I have a problem with my cyanuric acid level being too high. I understand that ideal levels should be between 25 - 50 ppm. Upon opening my pool for the summer, I discovered with a test kit that the level of cyanuric acid (stabilizer) in my pool was 100ppm. I found out from local pool suppliers that the normal reason for this is that prolonged use of stabilized 3" tablets (which contain c.a.), will result in high levels of residual c.a., after the chlorine has dissapated. They also said the normal fix is to drain some? water out of the pool and refill with fresh water. I drained about 2' of water out of an 18' x 36' pool and then refilled. The level of c.a. was then 80ppm. Not wanting to drain all that water out again, I reasoned that if I now used non-stabilized liquid chlorine for a period of time, some more of the c a would be diluted as I refilled the pool from normal evaporation. It has been about a month now and the c a level has gone back up to 100!

Where did I go wrong? Does anybody have any experience with this? Please help. I'm losing my confidence in the local pool suppliers. Thank you.

A reading of 100 on cyanuric acid is not too high. Levels should be between 30 and 100 and can be as high as 150 without causing any problems. Cya helps to keep the chlorine in your pool and keeps it from dissapating out to the sun. So a high or good reading is better than a low reading. You are fine, don't worry about it and don't waste anymore time or water. I would continue to use stabilized chlorine.

[waterbear]

A reading of 100 on cyanuric acid is not too high. Levels should be between 30 and 100 and can be as high as 150 without causing any problems. Cya helps to keep the chlorine in your pool and keeps it from dissapating out to the sun. So a high or good reading is better than a low reading. You are fine, don't worry about it and don't waste anymore time or water. I would continue to use stabilized chlorine.

You can run a pool with high CYA levels but you need to run higher FC levels and shock at higher levels also so there is enough chlorine in the water that is not chemically bound to the stabilzer and is available for sanitation. With a stabilzer level of 100 or higher you would need to keep your FC between about 8 to 15 pm and shock to about 25 ppm FC. This is the main reason that I do not like stabilzed chlorine. If you are currently at 100 ppm it is probably best to stop using it and use a non stabilized chlorine such as sodium hypochlorite (liquid) or cal hypo (which can sometimes be found as a slow dissoving stick for skimmer use...but do NOT put it into a feeder that had trichlor or use if you have an inline feeder....a very explosive reaction can happen! As far as your CYA level rising.....how was it tested? Did you do it yourself or was it done at a pool store. Was it done with strips (not very accurate for this test) or with a liquid reagent? (more accurate but still a very error prone test) The CYA test is one of the easiest to do wrong and get inaccurate results. If it was done by the same person under identical lighting then the results should match. If different people did it and had different testing procedures it is very possible for one to get 80 ppm and another to get 100 ppm with liquid reagent (melamine).

Also, refilling from evaporation will not lower the CYA. If there is a lot of splashout and you refill it might eventually lower the level but evaporation just concentrates everything in the water and the refilling dilutes it back to the level it was before. The ONLY economical way to lower the CYA is to drain and refill (Chemical CYA reducer is EXPENSIVE and will cloud the pool and require that you then let it sit and vacumn to waste. It is exactly the same thing as the CYA test reagent...melamine). If your level was at 100 ppm then a 50% drain would get you to 50 ppm.

[Brulan1]

You can run a pool with high CYA levels but you need to run higher FC levels and shock at higher levels also so there is enough chlorine in the water that is not chemically bound to the stabilzer and is available for sanitation. With a stabilzer level of 100 or higher you would need to keep your FC between about 8 to 15 pm and shock to about 25 ppm FC. This is the main reason that I do not like stabilzed chlorine. If you are currently at 100 ppm it is probably best to stop using it and use a non stabilized chlorine such as sodium hypochlorite (liquid) or cal hypo (which can sometimes be found as a slow dissoving stick for skimmer use...but do NOT put it into a feeder that had trichlor or use if you have an inline feeder....a very explosive reaction can happen! As far as your CYA level rising.....how was it tested? Did you do it yourself or was it done at a pool store. Was it done with strips (not very accurate for this test) or with a liquid reagent? (more accurate but still a very error prone test) The CYA test is one of the easiest to do wrong and get inaccurate results. If it was done by the same person under identical lighting then the results should match. If different people did it and had different testing procedures it is very possible for one to get 80 ppm and another to get 100 ppm with liquid reagent (melamine).

Also, refilling from evaporation will not lower the CYA. If there is a lot of splashout and you refill it might eventually lower the level but evaporation just concentrates everything in the water and the refilling dilutes it back to the level it was before. The ONLY economical way to lower the CYA is to drain and refill (Chemical CYA reducer is EXPENSIVE and will cloud the pool and require that you then let it sit and vacumn to waste. It is exactly the same thing as the CYA test reagent...melamine). If your level was at 100 ppm then a 50% drain would get you to 50 ppm.

40 percent of my customers use lithium hypochlorite because it is a non-stabalized chlorine for the last 36 years, generally speaking. I hate those tabs except when I go on vacation and I put them in a chlorinator.

40 percent of my customers use lithium hypochlorite because it is a non-stabalized chlorine for the last 36 years, generally speaking. I hate those tabs except when I go on vacation and I put them in a chlorinator.

avoid chlorine lock

[waterbear]

40 percent of my customers use lithium hypochlorite because it is a non-stabalized chlorine for the last 36 years, generally speaking. I hate those tabs except when I go on vacation and I put them in a chlorinator.

avoid chlorine lock

And it is the most expensive form of chlorine you can buy! You must like the profit margin from the sale of it! What is wrong with Sodium Hypochlorite! OR even Cal Hypo, with all its disadvantages....they are both unstabilzed chlorine also. Sodium Hypo is my first choice. It is cheap, readily availabe, easy to dose, and has minimal impact on water chemisty....even affects pH less tha lithium hypo!