Why no pucks without stabalizer

[chem geek]

The force be with you!

If it were easy to make a chlorine source that was slowly dissolving without CYA, then it would have been done already. It's not easy. There ARE Cal-Hypo pucks you can buy and these are essentially Cal-Hypo powder that has been compressed under high pressure into pucks. Technically, TriChlor tabs are made in a similar fashion.

Of course, with TriChlor pucks for every 1 ppm FC you add you get 0.6 ppm CYA. With Cal-Hypo pucks, for every 1 ppm FC you add you get 0.7 ppm CH. So one way or the other you are going to build up something you may not want. All things considered, the CH level isn't as critical so adding 50-100 ppm CH over a season isn't such a bad thing and is probably a reasonable option for some pools, especially if they drain/refill or dilute with winter rains to get ready for the next season. As has been mentioned on this forum elsewhere, some pools can use TriChlor pucks because the pools are smaller and their filters are backwashed regularly, so they can keep CYA under 50 ppm.

You CAN buy lithium hypochlorite which is a quick-dissolving powder and I suppose that someone could try and compress it to make a puck, or add some binders to it to hold it together (something else to add to the pool -- yech!), but this source of chlorine is VERY expensive. I have no idea if lithium causes any problems in pools -- it is in the same "class" as sodium and potassium, but does exhibit some unusual behavior in forming some compounds. It's probably OK. Too bad it's so expensive.

Richard