CYA high

[PeterDM]

7 years in, owning a small (12' x 24' x 5') vinyl pool. There've been some good periods ... & some bad periods, but overall I haven't really had a clue what I've been doing. I've used the basic test strips & periodic trips to the (not so) local pool store for water testing. I have NEVER used liquid bleach, only pucks & HTH granular hypochlorite.

The local pool store is a large, very professional company with a long history. Their water testing seems very professional with a computerized printout etc., however, even if they were reliable, they are a 25 minute drive away, so not very practical for day-to-day water monitoring.

After a bit of a struggle with algae this spring, the pool water is clear now. CYA readings are higher than ideal - the test strips indicate somewhere between 50 - 100, the last reading from the pool store was 63. One thing I wanted to clarify: does the granular hypochlorite add CYA to the pool? How quickly does CYA dissipate on its own? I will start using only liquid bleach from this point.

I need to order a proper test kit, which seems to mean ordering from the US & picking it up there (I'm about a half hours drive from the border), as the only recommended kit available (apparently) in Canada is the Taylor 2006C at $295 CDN (plus 13% tax).

 

[BoDarville]

Welcome to TFP!

...does the granular hypochlorite add CYA to the pool?

If you are referring to calcium hypochlorite, no it does not add any CYA to the pool. However, it does add calcium and if that gets too high, it could results in calcium deposits / scaling.

There are other forms of granular chlorine that can add CYA to the pool. You need to look at the label to note the active ingredient. If the label states "Dichlor-S-Trianzinetrione" (a.k.a., Dichlor) or Trichloro-S-Triazinetrione (a.k.a., Trichlor), these will add CYA to the pool.

Plain, unscented liquid bleach (sodium hypochlorite) is the best choice since it adds chlorine and a little bit of salt, thereby resulting in virtually no side effects.

How quickly does CYA dissipate on its own?

It depends largely on how many times the filter is backwashed, the rate of pool water splash-out, and rainfall. The more of these conditions that occur, the quicker the CYA level will drop. One of our Moderators had a CYA level of ~ 250 ppm when he discovered this forum and got it to gradually drop to the range we recommend, but it took a while (at least a year as I recall).