TA Equilibrium?

[Zalligan]

Hello All,

First full season starting for me and wondering - in a plaster pool, will TA finally reach a balancing point where it can't be driven any lower? I assumed with a SWCG, eventually, I would need to add product to bring my TA up to an acceptable range, given my regular acid dose to maintain pH, but that has not been the case. Over the last 3 months or so, I've added 3-4 gallons of MA to maintain pH, but my TA has been pretty consistently 70-80 and hasn't moved any lower nor higher. I had hopes of maintaining my TA around 60-70 this year to slow pH rise, but it doesn't seem I'll be able to get there, nor does it seem necessary, as my acid additions have reduced considerably.

Is there a TA "floor"?

 

[Texas Splash]

You don't want the TA any lower than 50. But if you want to bring it down from the 70-80 range down to about 60, that's fine. First let the pH rise to about 8.0, then use enough muriatic acid in one dose to lower the pH to about 7.2. That larger application of acid should help lower the TA a little better for you.

 

[mknauss]

If you are not adding alkalinity via fill water, the TA will typically get to a balance point in the 50 or 60 range that pH stays stable. I suspect you add fill water due to evaporation that has alkalinity in it. That is why your pH rises (not because of the SWCG) and your TA stays relatively stable with your acid additions.

 

[Zalligan]

If you are not adding alkalinity via fill water, the TA will typically get to a balance point in the 50 or 60 range that pH stays stable. I suspect you add fill water due to evaporation that has alkalinity in it. That is why your pH rises (not because of the SWCG) and your TA stays relatively stable with your acid additions.

This seems reasonable and makes the most sense even if the math isn't quite right. Wish the "effects of adding" could take into account fill water.

For reference, looking at my logs, my TA has been pretty much pegged at 80 since Feb 5. Since then, I've added ~1000gal of fill water with TA of 100 (though I probably need to re-check now that I'm more comfortable/familiar with my testing kit) and I've added 2.8 gallons of MA and 8 pounds of CYA.

Your mention of TA finding a balance point I think was the confirmation I was looking for in the question, knowing that it is something that happens is good enough for me to not be worried about anything!