Baquacil - High Alkalinity - High PH - Foamy water

tribalben · Postby **tribalben** » Mon 16 May, 2011 18:17

Hello all! I am fairly new to taking care of this pool, and in the past, only have experience with chlorine pools.

We are using the Baquacil CDX system ( which someone else converted the pool over to, before I started caring for it ) and are just now starting to really use the pool.

I have 8+ pH and about 240 TA. I have been trying to drop the TA with dry acid, but am not sure if what I am doing is helping it.

I would welcome any help!

Ben

Postby **chem geek** » Mon 16 May, 2011 20:31

Follow the procedure in how to Lower Total Alkalinity. It takes a lot of acid and aeration since your TA is rather high.

tribalben · Postby **tribalben** » Tue 17 May, 2011 00:55

Do I need to use the baquacil acid, or can I use standard dry acid?

Also, for aeration, will air coming in through a pump leak work?

Postby **chem geek** » Tue 17 May, 2011 01:11

Baquacil® pH Decreaser has "Sulfuric Acid, Monosodium Salt" which is another name for sodium bisulfate aka dry acid (sulfuric acid is H2SO4, sodium bisulfate is NaHSO4 so is a monosodium salt of sulfuric acid). So you can use standard dry acid or can even use Muriatic Acid if you want to.

As for aeration, I would not bring air into the pump but would instead just point returns upward to have the water flow break the water surface or make waves on the surface. If you have any fountains, waterfalls, spilloers, then you can turn those on.

tribalben · Postby **tribalben** » Tue 17 May, 2011 02:56

If I have a 25,000 gallon pool, how much acid is safe to add at one time? According to your directions, you say to bring the PH down, but in order to do that, it would take quite a bit of acid at once. Will that harm the pool?

Postby **chem geek** » Tue 17 May, 2011 12:36

It will take 2 gallons of full-strength Muriatic Acid (31.45% Hydrochloric Acid) in 25,000 gallons to lower the pH from 8.0 to 7.0 and this can be added SLOWLY over a return flow in the deep end with the pump running. After you add the acid, lightly brush the side and bottom of the pool where you add the acid in order to ensure thorough mixing. The key is to pour the acid into the water flow so that it gets dispersed. If you pour too quickly, it can pool to the bottom. Brushing also helps to mix up any acid that may not have dispersed enough, especially if you don't have any floor drains.

The 2 gallons of acid will lower the TA by 39 ppm so you'll still need about 6 gallons more to get the TA down to 80 ppm, but obviously this won't be added all at once. Instead, when you aerate the water the pH will rise with no change in TA. You then add more acid to lower the pH back down to 7.0. For example, if the pH rises to 7.2, then adding about 10 cups of acid will lower the pH back down to 7.0 when the TA is at 200 ppm. As you get lower in TA, the rate of pH rise will slow down and the amount of acid you need to add will drop. For example, when you get to a TA of 100 ppm, it only takes 5 cups of acid to lower the pH from 7.2 to 7.0. You can wait for the pH to rise more before adding acid, but the process will take longer since carbon dioxide outgasses faster when the pH is lower (see this table).

The Lowering TA process works because of what is described in the table in this post that gives instructions for the process.

What you are doing is simply accelerating a process that would have occurred anyway. Your high TA would have your pH get high, you'd add acid to lower the pH which would also lower the TA, then the pH would rise again, etc. You cannot avoid adding acid, but you can speed up the process via aeration. Then, with a lower TA level, the pH can be more stable so you don't have to add acid as frequently or in as much quantity in the future. It's a pay-me-now vs. pay-me-later choice.