Quote Originally Posted by chem geek View Post
As with any acid, it brings down both pH and TA together, though the pH drops more than the TA. This assumes you are using Trichlor for a while so there is chlorine usage/consumption. For example, adding 3 Trichlor tabs/pucks to a 10,000 gallon pool starting out with a TA of 100 ppm and pH of 7.5 would end up with a pH around 7.0 and a TA of 88 ppm. In practice, the pH might not drop that much since there will likely be outgassing of carbon dioxide during that time. The cumulative FC added and presumably consumed is 16 ppm and the CYA increase is 10 ppm.

Don't forget that for every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.

Richard
Thanks very much, Richard. I chlorinate using a SWG and sometimes have to use muriatic acid to either bring down TA or PH. I've never used a puck before but I assume you have to leave it in a skimmer or feeder for a while and so it sounds like it wouldn't be good for my purposes. I have a vinyl lined pool and I'm still a little nervous about using the muriatic acid. I do pour it into a 5 gallon bucket first and then pour in front of the returns. I also have some dry acid but I hear that's not so good to use with a SWG, but I can't remember why.