Something I was wondering... My old 3" puck said the ingredients were 99% tricolor and the other 1% was not listed as CYA. Where does the CYA come from in the puck? Is it a byproduct of dissolution of the tricolor or an unlisted ingredient?
Trichlor is a chemical combination of chlorine and cyanuric acid in the same molecule (see Trichlor vs. CYA). The 1% are binders and minor impurities. This is why the relationship that for every 10 ppm FC added by Trichlor the CYA increases by 6 ppm holds true regardless of concentration of product or of pool size.
Old thread, but exactly what I was looking for. If I want to raise my CYA from 30 to 35 (or 40), all I need to do is chlorinate with pucks for a few days (since I have spares laying around), right? Maybe 4 or 5 days, turn off my Clorox feed and throw the plastic puck float in the pool (or run them through the auto-feeder). Don't want to buy CYA if I can use up old tablets.
In your 15,000 gallon pool, four 3" 8-ounce tablets would increase FC by 14.6 ppm and CYA by 8.9 ppm. Tablets in a floating feeder typically take about a week to dissolve completely though it depends on the feeder. That's probably just about the amount you'll need to keep up with 2 ppm FC chlorine demand, but you should keep an eye on it and supplement if needed.