Trouble reducing TA

[Vesuvius]

Opened the pool 3 days ago with initial TA measuring 110 (via Taylor K-2006). pH was super high, so I added (over several different dosings) 154 oz of Acid Magic. This reduced pH levels as expected per PoolMath but only dropped TA to 100 (PoolMath indicated it should drop by 21 to roughly 90). So, I've been adding more Acid Magic and aerating repeatedly trying to bring down TA. Every time, the pH drops as expected but TA continues to hover at 100-110. PoolMath Summary shows that I've now added enough Acid Magic to reduce TA by 56 cumulatively. This is baffling to me. We did have some rain the first day or so but otherwise, I've added no water and nothing else to the water but liquid chlorine, salt, liquid stabilizer and calcium chloride. And it can't just be the rain, as I've had several rounds of acid/aeration since it stopped and TA still does not budge (has actually increased a bit from 100 to 110 this morning).

I know one response will be "just use regular MA." This is my 1st time maintaining the pool and Acid Magic has always worked as expected in my spa, so I wanted to at least start with this to reduce the number of new things to figure out. I know straight MA is cheaper. There must be some explanation for why AM works as expected in my spa and works as expected relative to pH in the pool but not TA.

Another response may be "just ignore TA and see if pH is stable enough at 100/110." The issue is that I have an elevated fountain/waterfall that spills over into the pool and this is pushing pH higher pretty quickly. I've cut down the run time from 15 mins 3 times/day to 8 mins 3 times/day but want to run it enough that I don't get nasties growing in the basin.

Appreciate any thoughts!

 

[PoolStored]

Acid Magic

Acid magic is muriatic acid. The SDS does not list the %. My guess is that the % in Acid Magic is lower than the % you used in PoolMath.

 

[Vesuvius]

Acid magic is muriatic acid. The SDS does not list the %. My guess is that the % in Acid Magic is lower than the % you used in PoolMath.

I saw somewhere that it's 31.45% (20 Be) and the pH changes I get from PoolMath for that strength match what I get in my spa and pool water, so I think that must be accurate.

 

[PoolStored]

Then ignore it and just manage pH. What is the TA of your fill water? Do you have an autofill?

 

[Vesuvius]

But why would TA not be moving along with pH? I don't want to be adding MA multiple times/week, especially as I travel a lot during the pool season, so want to get things tightened up so that I can get that down to once per week (or 2 if I'm lucky).

TA of fill water is only 80. Nope, don't have an autofill.

 

[PoolStored]

Curious. Don't know.

Suggestions.
Are you wiping the tip of the R009 with a wet paper towel between drops. Try that.
Clean your test equipment with rubbing alcohol and retest.
Do you have a speed stir? Might consider getting one. Brother who had a pool for 30 years and I did a test. Him swirl and me with speed stir. His results were a drop higher because the swirl did not swirl as good as speed stir.
You might try a different brand of muriatic.
Don't know how far you lowered pH each time. Try reducing pH to 7.0 (do it it back to back additions, add, test 30 minutes later, repeat until you get to 7.)
How old are your reagents?
How are you aerating?

 

[Jimrahbe]

V,

When I lower my TA is takes me about two full days..

1. Test pH and TA.. Record both. Turn on and leave on your aeration source.
2. Reduce your pH to about 7.0
3. Two hours later test your pH and reduce again to 7.0
4. Repeat step three over and over until your TA drops to 50
5. During this process, test TA every 4 to 6 hours until you see the TA dropping. It will drop slowly at first and then it will start dropping faster, so you should test the TA more often.
6. I test from morning until time to go to bed. I leave the aeration on, but stop adding MA until the next day.
7. The next day I start again until I drop the TA to 50.. It will jump back up to 60 pretty quickly.

I guess my point is that it is a long process, not a one and done thing.

Thanks,

Jim R.

 

[PoolStored]

@Jimrahbe is spot on.

Two things to remember.
CO2 outgassing is highest between pH of 7.0 and 7.4. If you can catch it at 7.4 and reduce to 7.0 as your cycle it will go faster.
You want to make LOTS of VERY TINY bubbles. I built this on a sump pump and can reliably reduce TA by 10 in 12 hours.

Aerator.jpg

• PoolStored
• Sep 11, 2022
• 2

 

[Vesuvius]

Curious. Don't know.

Suggestions.
Are you wiping the tip of the R009 with a wet paper towel between drops. Try that.
Clean your test equipment with rubbing alcohol and retest.
Do you have a speed stir? Might consider getting one. Brother who had a pool for 30 years and I did a test. Him swirl and me with speed stir. His results were a drop higher because the swirl did not swirl as good as speed stir.
You might try a different brand of muriatic.
Don't know how far you lowered pH each time. Try reducing pH to 7.0 (do it it back to back additions, add, test 30 minutes later, repeat until you get to 7.)
How old are your reagents?
How are you aerating?

1) no, will try that
2) i did that day or two back, so doubt that's the problem but will do again
3) yes and I use it for the TA testing
4) ok, thanks
5) generally i've been reducing to more like 7.1, as I didn't want to overshoot and end up in the 6s. Will push for 7.0 going forward
6) reagents all within effective dates on the bottles
7) via running the overflow waterfall

 

[Vesuvius]

V,

When I lower my TA is takes me about two full days..

1. Test pH and TA.. Record both. Turn on and leave on your aeration source.
2. Reduce your pH to about 7.0
3. Two hours later test your pH and reduce again to 7.0
4. Repeat step three over and over until your TA drops to 50
5. During this process, test TA every 4 to 6 hours until you see the TA dropping. It will drop slowly at first and then it will start dropping faster, so you should test the TA more often.
6. I test from morning until time to go to bed. I leave the aeration on, but stop adding MA until the next day.
7. The next day I start again until I drop the TA to 50.. It will jump back up to 60 pretty quickly.

I guess my point is that it is a long process, not a one and done thing.

Thanks,

Jim R.

Thanks, Jim. This "test/acid/aerate/repeat" approach is basically what I've been doing, except I've been adding acid 1-2 times/day rather than every 2 hrs. I still don't understand why this slower approach hasn't moved the needle, when PoolMath says it should've dropped it by 56 by now, but I'll get more acid and try this.

 

[Jimrahbe]

I still don't understand why this slower approach hasn't moved the needle

V,

I can't even spell Khemistry, so I have no idea why, but for me it goes down very slowly at first, and the more you do it the faster it drops..

I have not done this recently as my TA is now pretty stable at about 60. But when I had to do it, my TA was like 110 or 120.. The 2-hour requirement can be adjusted so it works well for you.. The point is that adding MA twice a day is never going to get you there.. After two hours if your pH is only 7.1 or 7.2, then you need to wait until it gets in the 7.4 range.. I think how fast your pH increases is directly related to the amount of aeration you have.

Thanks,

Jim R.

 

[Rancho Cost-a-Lotta]

What's your current borate level?

 

[Vesuvius]

What's your current borate level?

Yeah, that's on the to-do list--I bought all the stuff needed to test it and ordered boric acid from Duda. I'll test once I have the acid, but my assumption is it will be 0.