Chlorinator question

[Sumo1]

I think this is the right place to post this. Our church pool has four pumps/filters and four 29" in-line tablet chlorinators. Each chlorinator holds 12-13 three inch tablets and we've had them refilled on about a four day schedule since the pool re-opened last June. No tablets were used from about mid-October until April. Our problem is a high cyanuric acid level around 100. Our chlorine level is around 10, which is not all that high, considering the CYA. I, however, would like to run the pool with the CYA closer to 50. My question is: Should I stop the tablet usage (probably for the rest of the summer) and let the CYA be reduced through rain and backwashing, etc. or should I quit worrying about it and be happy with the great pool we've got?

Hal

[chem geek]

Stop using the Trichlor pucks/tabs unless you want the CYA to get even higher. For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases CYA by 6 ppm. A little math shows that even with low 1 ppm FC per day usage, Trichlor will increase CYA by over 100 ppm in 6 months. At 2 ppm FC per day usage, it only takes 3 months. Only dilution of water (backwashing, splash-out, rain overflow) will lower the CYA level.

Are you able to use chlorinating or bleach as your source of chlorine for this pool? You'll have to add it every day (or possibly two) unless you use a pool cover of the pool isn't exposed to direct sunlight. With the CYA near 100 ppm, you'll need to maintain an FC of at least 7.5 ppm FC (Ben's chart says 8 ppm). If you have to have a lower FC, then you'll need a supplemental algaecide at extra cost, but this is not necessary if you maintain sufficient FC relative to CYA.

Richard