CYA Level After Adding Tablets

[DanF]

I sanitize my pool with an SWCG, but CYA level has dropped a bit (to 60) so I decided to use trichlor tablets I had on hand to bump it up. Specifically I put 32 oz of trichlor (4 tablets) in a floater 10 days ago. Water temperature is in the mid 80s. Today there is about 10% of the tablet volume remaining in the floater, but my tested CYA level hasn't changed - still about 60. I tested it 3 times with my K-2006C, the last time using the larger view tube from TFTest kits.

FC levels definitely went up, so I know the tablets are OK. Does it normally take this long for the CYA levels to change upon testing? Wondering if I should add more tablets or wait a while and retest, as I don't want to overshoot.

 

[Oly]

As you probably calculated 32 oz of trichlor should add 10ppm CYA.
You should test again after a few more days. If still at 60 then I would use two more tabs, 16oz, and check again several days after fully dissolved. The test is not very precise and is why we round up our results for in between results. I like adding in 5ppm increments as I approach my goal.