Do I have to use CYA?

[chem geek]

yjjeeper,

You do not have to worry about the CYA in the pool as far as toxicity is concerned. Yes, it would be fine to have a lower CYA level if you are concerned and it might mean you need to add more chlorine each day, but the toxicity level of Cyanuric Acid is for concentrated doses, not the very dilute amounts found in a pool.

Of everything that is put into a pool -- chlorine, CYA, carbonates, calcium, chlorides, PolyQuat algaecide, borates -- the only item that appears to be toxic at normal pool levels is the Borates if a dog regularly drinks from the pool every day. Even then, the toxicity is around the "first symptoms" level and no where near serious death or immediate problems. So some people avoid using Borates in the pool if they cannot teach their dog not to drink from it, but I don't think CYA is a problem at these levels -- at least I can find nothing to indicate that.

For example, for CYA, the acute toxicity level for fish is > 2100 ppm. For aquatic plants, levels above 320 ppm result in somewhat slower growth. For rats, > 5000 mg/kg of body weight resulted in no deaths (no lower doses were tried). The repeated dose tests at maximum liquid solubility of around 5375 ppm as well as lower doses showed no changes in body weight, food consumption, slightly higher water consumption at the highest doses (5375 ppm) but normal at 1792 ppm and below, or even kidney weight changes. You can see the full report here.

Obviously, from the cat food incident, the combination of CYA and melamine is very, very serious, but there should be no melamine in the pool nor in (proper) food, etc.

Richard

[yjjeeper]

Richard, thank you for the info and the link all very helpful. After doing further research, I agree the minimal levels of CYA do not look like they will cause any harm.