Ta And Ph Issue

[jennaemac]

I bought SPA CHOICE Reduce pH online. It said on the website that it would correct high TA but on the bottle it only mentions pH. How can it lower both pH and TA? I have been battling my water all day and right now after adding about 4oz of this stuff my pH is 8.3 and TA is 190. Its bouncing quite a bit and Im not sure if this product is misleading or if Im not understanding something. Im not exactly new at this (2 years with Arctic) but we have always used Arctic chemicals and Im trying something different now with latest water change just because arctic stuff is so hard to get in my area. Has anyonw used this stuff? I cant seem to find a product that says it will lower TA so I feel like Im missing something. We always have high TA after a water change and have always had to lower it and I have never had these problems before.

[Maxemily]

Two choices:

Dry acid or muriatic acid will reduce both TA and PH.

I have not used dry acid, but I understand it is safer than muriatic in that should you spill there will be no issues if it doesn't get wet.

As far as muriatic acid is concerned - available at any hardware store - you would add 2 oz. at a time running the spa for 10 minutes and checking TA and PH. Reduce to 1oz at a time as you near the target values.

[tony]

PH down, PH reducer, TA down, TA reducer, Alk down, etc are generally all dry acid. It reduces both pH and TA.

[chem geek]

While any acid will lower both pH and TA since they move together when adding strong acids or bases, if you want to lower the TA more than the pH or if the pH is OK but the TA is too high, the only procedure to do this is a combination of acid addition with aeration, done at a low pH. The procedure is described in this post.

In your situation, with a pH of 8.3 and a TA of 190, adding a strong acid to get the pH to 7.5 would only lower the TA to about 180. Though they move together, the TA doesn't go down very much. There is NO product that will only lower the TA. Basically, the high TA is due to over-carbonation of the water (too many carbonates) and the ONLY way to remove them (other than causing scaling to precipitate them -- do NOT do that) is to drive the carbonates out of the water as carbon dioxide gas. You do this by aerating the water (i.e. running the jets) at low pH (around 7.0) while adding acid to keep the pH low. Aeration raises the pH with no change in TA so as the procedure link shows the net result is a lowering of TA.

As long as your TA is high, then your water will tend to rise in pH, especially when there is aeration. The TA lowering procedure simply accelerates the process that would continue to occur over time. You end up adding the same amount of acid as you would over months, but you get this over with faster via the low pH and aeration. The pH will be more stable when the TA is lower (but not too low -- stop at 80 ppm and see how things go, depending on the type of chlorine you are using).

Richard