Too-frequent pH lowering?

[brunoforestier]

I have a similar scenario to the one described here:

Muriatic Acid Needs

I’m running into a similar problem as the following: Muriatic Acid Question The pool is chugging muriatic acid weekly and I’ve yet to test and find the Ph lower than 8.2 which is the top of my scale. I’ve read a SWG exhibits this problem but never thought it could raise Ph so much so fast. TA...

www.troublefreepool.com

My pool:
TA: 50
CYA: basically zero - it's an indoor pool
Calcium: 300ppm

I keep the FC between 1.5 and 3.0

My problem: I am putting 8oz of 31.45% Muriatic Acid in about every 7 days to lower the pH from 8 to 7.6. I've been doing this for 2+ years and decided to post about it now that I'm low on Muritic Acid and it's no longer easy to buy at Home Depot.

Is this normal? That thread I referenced above mentioned high TA as a cause for needing to lower pH. But I don't have high TA levels.

An interesting tidbit: When I cover my pool in the winter months, the pH remains constant and does not need adjustment.

Thanks

 

[mknauss]

You are adding water to the pool, correct? What is the TA of the fill water?
When you cover the pool, you do not have to add much water and you have virtually no aeration. Same thing happens with my pool when I use the solar cover.

 

[brunoforestier]

Great question! Fill water is also 50 TA.

I follow the logic of the no cover/aeration contributing to the pH rising. But I can go a couple of weeks between water fills and still see a rise in pH.

 

[mknauss]

With no CYA, your TA is largely carbonate alkalinity.

Let the TA come down to 30 or 40 and see if that stops the pH rise.

 

[brunoforestier]

I'll start lowering the TA later today and report back.

One hypothetical: Let's say I do get the pool to 30 or 40 TA and that keeps the pH at 7.6.... how do I deal with the fill water of 50TA and keeping the pool water in the 30-40 range? I guess I'd just have to perform the TA lowering exercise periodically?

 

[Dirk]

My pool never did stop thirsting for acid, as many do. Though I have high TA fill water to blame. I automated acid dispensing. Still gotta buy acid, but I don't have to handle it much any more. I use an IntellipH, which works as a companion to my Pentair IntelliChlor SWG. Together they greatly reduce my maintenenace chores, and in the case of chlorine, the IntelliChlor greatly reduces the cost. Neither is a cheap solution, but they do end up paying for themselves, especially with the current high cost of chlorine. Something to think about, anyway...

 

[mknauss]

I'll start lowering the TA later today and report back.

One hypothetical: Let's say I do get the pool to 30 or 40 TA and that keeps the pH at 7.6.... how do I deal with the fill water of 50TA and keeping the pool water in the 30-40 range? I guess I'd just have to perform the TA lowering exercise periodically?

You will just monitor pH and when it gets to 8 or above, lower it to 7.6. That should lower the TA.