Thank you, I've read through that post numerous times, and many others, but I'm not seeing what I am looking for. Also, I saw where Watermom indicated the 10 to 6 relationship of chlorine to CYA in trichlor. I think what I am not making clear is that I'm trying to estimate what the impact will be before I put the pucks in, to determine how many to start with. For example, with bleach we have the calculators that tell me if my pool is a certain size, I need to put in a certain number of oz of bleach to raise my FC level 1 ppm. So my question is, how can I estimate the rise in FC and CYA from one puck of trichlor? Also the drop in pH?

I know that it takes time for these pucks to dissolve, and once they have done so, the CYA is already in the pool, and difficult to remove. I've also read that it may take several days after it's put in to register, which has me worried that even if I take them out, the level could keep rising. I want to sneak up on the desired level, and not have to worry about shooting way past it. So if one puck has the potential to raise my CYA by 10 ppm, then I'll just put in one at a time, and then test several times after it's dissolved. But if one puck is only likely to raise CYA by 1 ppm, then I'll put in 5 or 6 at a time, and not be so worried about shooting way past my goal.