Question about using dichlor granules to replete CYA

Aug 31, 2016
Greetings fellow TFPers!

I have a general question, and I'm hoping someone can answer it for me. I'm opening my pool (filling atm) today, and I fully anticipate my CYA to be way too low-- probably will be around 20ish.

I wasted money buying some of these 1lb bags of Clorox Shock Plus that are 58.2% Sodium dichloro-s-triazinetrione last year, but I'm hopeful that I may have a temporary use for them here while I'm trying to bring my CYA back up to acceptable levels.

I used PoolMath and I found the neat function at the bottom where you can put in an "oz" figure and select a chemical. My question is this: Is the "dichlor" chemical selected from the dropdown box comparable to the 1lb bags I have here? I put in ~16oz roughly for the 1lb bag I'd be adding, and it returned back that for each bag it would roughly raise my CYA by 3 (for a 20,000 gal pool). Can I trust this calculation? If so, would I have any problems using say.. 10 bags of this dichlor in addition to whatever extra bleach I need to maintain my SLAM figures?



TFP Expert
Platinum Supporter
May 23, 2015
Tucson, AZ
You can trust the Effects of Adding Chemicals section but the dichlor listed there is for pure 99% dichlor. The Clorox stuff you bought is not pure dichlor but a mixture of chemicals - dichlor, borates and floc (aluminum sulfate). That last part is a bit concerning because adding floc to a pool is unnecessary in most instances. If the floc does cause anything to fall to the bottom of the pool, you will need to vacuum to waste to get rid of it.

You'd be better off just using pure granular CYA to raise your levels independent of the other chemicals. You can use the clorox stuff if you want but it's not going to add as much CYA as PoolMath calculates and it's going to add other stuff with it that you don't need...