Does using CO2 raise TA?

[FCCinAZ]

I recently added borates to my salt water pool and as directed, I lowered my TA to 80. As expected, pH rise still occurs although more slowly with the borates. I add about 1/2 gal of 14% MA weekly to keep my pH 7.3-7.6 per Taylor 2006. My latest test results are: NaCl 3500 ppm, CH 320, Borates 50 ppm, CYA 80, TC/FC 4, pH 7.6 temp 93. I notice that as the pH trends up, I get calcium deposits on the SWG and want to maintain a constant pH.

On on my previous pool, I fashioned a CO2 delivery system for under $175 utilizing a CO2 injector from commercial pool company (check valve, injector and diffuser for $50), an old 20 lb CO2 canister from my Jeep days, and a CO2 regulator with a controllable and adjustable flow rate ($80 on a hydroponics web site). On my last pool, I infused low and slow for fixed time every night with the tank lasting about a month. I didn't have a reliable test kit with that pool, so I can't say what happened to my TA. It did keep my pH below 7.6 in a 30k gallon pool. My current pool is much smaller.

While I'm pleased with the stabilization I got with the borates, I'm contemplating rehooking up the CO2 infuser for pH control but fear that my TA will rise. Given the added difficulty of lowering them again, I am hesitant. I've seen posts repeatedly stating that TA will rise, but others state that it won't. Anyone have a definitive answer to that question or different suggestion for automated pH control?

 

[Patrick_B]

Welcome to TFP,

I don't see how it's possible for Co2 to add TA. Excess Lye in Bleach or another source, but I think not with Co2. I do think using Co2 as a primary pH control source is highly impractical when it's so easy to do with Acid...which consequently addresses your rising TA concern. Why are you opposed to using HCL?

 

[FCCinAZ]

Welcome to TFP,

I don't see how it's possible for Co2 to add TA. Excess Lye in Bleach or another source, but I think not with Co2. I do think using Co2 as a primary pH control source is highly impractical when it's so easy to do with Acid...which consequently addresses your rising TA concern. Why are you opposed to using HCL?

I don't have any concern using HCl, but the thought of animating the process appeals to me and handling CO2 is less messy than keeping a bucket of acid hooked up to a Stenner pump. Given our water hardness, I'm really getting aggressive with keeping pH below 7.6 to keep me on the negative side of the index because I'm tired of replacing SWG power units and cells.

Thanks for your reply. I never understood how CO2 would raise TA, but several places reference that. Guess I'll hook it up and see what happens.