I'm trying to lower my TA. My TA was 120 last night. After putting 40oz into my pool about 18 hours later the TA is still the same. I put 40 more oz in. The Sodium Bisulfate I have was keep in a shed and is probably 2 years old. Should I assume that it is no good. When should I test and be able to see a difference if it is still good.

We usually call Sodium Bisulfate dry acid. Dry acid has an extremely long shelf life. It is almost certainly still good.

The primary effect of adding dry acid is to lower the PH. When working on lowering TA, you need to keep a close eye on the PH and use that as a guide to how much acid to add, rather than going by the TA. You don't want the PH going below 7.0 at any point.

Complete instructions on lowering TA are available in Pool School.

Guess I should have read it more carefully. Looks like PH can vary as quickly as 30mins.



According to the pool calculator I need to add 43oz of dry acid to get PH down to 7.0. So should be I checked PH hourly and constantly adding acid? I'm confused. I don't want to add too much too fast when I should be waiting for a slower change in PH and TA.

Drop pH to 7.0

Run the pump and aerate as much as you can - fountains, waterfalls, spa jets, or a homemade aerator. Search that term here and you find some good ideas.

Give it a couple hours (or less if you're antsy) and recheck pH and TA. Add whatever acid you need to get pH back down to 7.0.

Repeat.

You won't see a lot of TA drop each time, but pH will keep coming back up. Pool Calculator will tell you the effects of adding chemicals, down near the bottom. You'll see that you may expect 5, 8, maybe 10 ppm drop on TA each time. So you can probably skip the TA testing some times to save reagent. When TA starts getting close, then pay close attention. And stop the vigorous aeration, lest it drop too low.

Pool is starting to clear!

Second application of dry acid did nothing so I'm gonna assume its no good. The muriatic acid worked though, PH is down to 7.0. TA is at 90. I picked up some pvc and adapters to make a homemade aerator. I'm excited. I feel like I kid with a new toy with the K2006. Its nice to feel more in control of my pool and not be at the mercy of the pool store. Thanks so much to everyone on here.