pH won't go down

Jump to latest Follow Reply
M

mylabspool

0
Sep 11, 2012
5
Early this season my pH was a little low so I added 1 4LB box of borax. It moved from about 7.0ish to 7.6. I was happy.

But continuing over the course of the summer and now into September I've been adding pH down because the pH has gone to 8.0! Over the course of a month or so I've added about 4x what the bottle said to add in attempt to reduce my pH from 8.0 to about 7.4-7.6, but it's stubbornly held around 7.9-8.0.

I've been using an acid salt called Sodium Bisulfate(93.x%) which I've purchased at Lowes and/or Home Depot.

Is it normal to have to add so many times more chemical to reduce the pH?
What other things can I try? I obviously want to be careful because I don't want to overshoot and go too low on pH.

I have a 24K gallon IG Vinyl pool and use liquid CL.
FC this morning is 8.0, usually closer to 4ish but I recently shocked.
CC = 0 which is typical
TA = 100
pH = 8.0
CYA = ~50

Thanks in advance for the help!
 
Muriatic acid was my first choice, but it doesn't seem that Lowes or HD sell it anymore. They sell something else called something like "safe muritic acid." Not sure what it was so I went right to the pool section and used the pH down Sodium Bisulfate. Is muriatic acid more effective? Any suggestions on where to get it these days?

Thanks
 
the safe acid I think is a code word for weaker strength. I will work, but will take more. That is one product I do buy at a pool store which seems to be a decent deal.

Posted from my Droid with Tapatalk ... sorry if my response is short ;)
 
As your TA decreases due to acid additions, you rate of PH rise will also decrease and hopefully stabilize. If you have a source of aeration, such as a waterfall, swg, fountain or just lots of kids splashing around, that can also make PH rise.

I get my MA at the hardware store (ace or true value) in the paint aisle.
 
Just to be clear the Dry Acid you are using works - it's just that you have to use something like PoolCalculator.com to determine the correct amount to use and MA is preferred. MA doesn't add anything you don't want in the pool, dry acid adds sulfites over time which can eventually be a problem.

If you have a test kit and can measure your TA and your Borates ppm input your pool size, pH and that info and you should get a fairly accurate calculation for lowering the pH. The borates ppm you may have to measure with a test strip or use a pool store to get.

The safe MA is about 15% (half-strength) so you lug a lot more water around but it works the same as normal MA. My HD carries MA (Full Strength 31.45%) but my pool store does not carry any MA at all. They also don't carry liquid chlorine - don't get me started!
 
Don't buy that Safe acid stuff.... It is horrible... I have used 2 gallons of it and never got my PH down past 7.6... Just got some 31% stuff at lowes in the paint removal section and used 20 ounces... 30 minutes later ph was 7.4
 
Sodium Bi-Sulphate is a Dry Acid used commercially in pools, especially larger indoor pools, i'm surprised it hasn't moved your pH level atall as it is pretty potent stuff usually and should shift it.

The only think I can surmise is it is a cheaper version which has been blended with other items to make a cheaper form of the chemical, and you will just need to add more to get it to start moving in the right direction.

It may also be the case that your TA at 100ppm and the combination of the added borates is holding your pH higher, you might want to drop TA down to around 80/90ppm and see if that makes things a bit easier to control.

Regards
Stu
 
Stuamurr said:
It may also be the case that your TA at 100ppm and the combination of the added borates is holding your pH higher, you might want to drop TA down to around 80/90ppm and see if that makes things a bit easier to control.
Click to expand...
Dropping the TA is done with ACID as well so perhaps two birds with one...
 
Stuamurr said:
It may also be the case that your TA at 100ppm and the combination of the added borates is holding your pH higher, you might want to drop TA down to around 80/90ppm and see if that makes things a bit easier to control.
Click to expand...
^^^This^^^

TA and borates are both pH buffers. Both are in your pool trying to keep pH from moving, so it's going to take a lot of acid to get your pH to move.

Sent from my Exhibit II using Tapatalk.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Had the same problem and used PHDown weekly, sometimes every 4-5 days. Then, when I ran out of liquid chlorine I used 10-15 aquachem dual layer tablets then went back to liquid - PH hasn't been a problem since (for remaining month or two until pool closed).
My readings were similar to yours, except my CYA was around 35 before I started with tablets and I used PHDown when PH reached 7.8
 
LeeM2 said:
Had the same problem and used PHDown weekly, sometimes every 4-5 days. Then, when I ran out of liquid chlorine I used 10-15 aquachem dual layer tablets then went back to liquid - PH hasn't been a problem since (for remaining month or two until pool closed).
My readings were similar to yours, except my CYA was around 35 before I started with tablets and I used PHDown when PH reached 7.8
Click to expand...


That's right...tablets are acidic, so they kept PH in check while dropping TA. As long as one maintains a higer FC due to CYA increase, it's not a problem, plus it helped you chlorinate. However everyone's individual pool is unique and to solve just PH rise, dropping TA is the answer and if that still can't stop the rise, borates is yet another option.
 
I purchase MA from both Lowes and HD. At HD the "real" MA is kept outside, only the "safe" type is inside by the paint. Make sure you ask someone to confirm they don't have the good stuff stashed somewhere.
 
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply