A quick circle back about some secondary things brought up in this thread -
By now, you likely have a sense for the relationship between CYA and CL. Withing limits, CYA helps slow the daily loss by holding CL in reserve - but our tests only track the total CL, hence the higher targets called for as CYA increases, in order to maintain enough active CL.
Leslie's was not totally wrong, as tablets can be used to replace CL when the SWCG is not running. But, the tablets contain stabilizer (CYA) too, so the more you use, the more you need - until the need gets to an unsustainable level. Tablets dissolve - and the rate is very temperature dependent. So it can be really hard to determine any accurate dosing amount. It may take a couple of days in the summer, or a couple of weeks in the winter. Best one can do is test daily and add/subtract the number of tablets and chase the target blindly (I know, as a former 30 yr tablet guy). And test CYA weekly, to make sure it is not building to impossible levels. The only way to reduce CYA is to drain the pool.
Hence the strong preference here for: 1) Add stabilizer separately to get to a target level. Then add no more. And: 2) Use only liquid, since it only adds CL and nothing else. Of course, in warmer weather, no liquid needed normally at all, since you have a SWCG.
The one time the tablets may be useful - when leaving the pool unattended for a longish time. Each of us has our own comfort level about how long we want to leave things operating without any attention. Filters or skimmers could clog. Power outages could happen. Etc. But if you will be gone for 2 weeks, which might be 10 days longer than your comfort level - one can build up the CL using liquid to SLAM level, turn it all off, and then toss a floater or two with tablets in for kind of timed release. There still may be a chance you return to something brewing, or it may be just fine (except for leaves/worms on the bottom!). But you did what you could to forestall problems. So if your tablet supply is small, you may want to hang on to them for this. They don't go bad as long as well protected from moisture.
Just don't use tablets for normal chlorinating, unless you are deliberately trying to build up CYA slowly.
www.troublefreepool.com
