TA level question

[Tie Twist]

From Pool School:

"If you are using trichlor tablets for chlorine, follow the bleach recommendations but have TA around 100-120 and be sure it doesn't fall below 100."

I use 12% Chlorine to chlorinate, but I am curious about the above statement. Does it have to do with the acid lowering PH in the tabs?

I am in Canada, and so I have only the OTO test kit, but I am doing a good job on the pool (if I do say so myself!). All levels are great, and my pool store actually does a decent / consistent job testing from what I have seen, i nthe 2-3 times per year I get them to test. usually I want to know CYA and TA. My TA always runs around 90-100, but when it is under 100, they always suggest to increase it, which I never do. I wonder if it relates to the above, and the assumption I am using tabs, although I suspect they don't really understand why they recommend it should be higher. Their own printout recommends 80-120, but they say it's wrong...lol.

Just a curiousity.

Thanks.

 

[JasonLion]

Yes, trichlor constantly lowers both PH and TA. To keep things stable you need TA higher than you would otherwise want it. At regular TA levels the PH would go down so quickly there would be trouble.

Pool stores just assume you are using trichlor, so they always recommend high TA levels. High TA isn't usually a huge problems when using liquid chlorine, but it gets to be a real problem when you have a waterfall, fountain, or SWG (which cause aeration). High TA plus aeration will result in rapidly rising PH.

 

[Tie Twist]

Awesome, thanks.