Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 14 of 14

Thread: pH won't go down

  1. Back To Top    #1

    pH won't go down

    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!

  2. Back To Top    #2

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,085

    Re: pH won't go down

    Use the poolcalculator and muriatic acid. Your pH will go down.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  3. Back To Top    #3

    Re: pH won't go down

    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

  4. Back To Top    #4
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Location
    Tucson, AZ
    Posts
    37,389

    Re: pH won't go down

    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
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  5. Back To Top    #5
    dmanb2b's Avatar
    Join Date
    Apr 2009
    Location
    NY
    Posts
    3,728

    Re: pH won't go down

    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.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

    Pool School, TFTestKits, Pool Calculator

  6. Back To Top    #6
    UnderWaterVanya's Avatar
    Join Date
    Jun 2012
    Location
    Mint Hill, NC
    Posts
    2,589

    Re: pH won't go down

    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!
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
    Hayward SuperPump (model ?), Polaris 380 & PB4 Booster Pump

  7. Back To Top    #7

    Re: pH won't go down

    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
    18x36 Grecian Vinyl; 8' Roman steps w/t 2 spa jets; cozy cove w/t 6 spa jets; 2 MD, 1 Skimmer, 3 returns; Hayward Ecostar, 30" Ranger sand filter; Hayward color logic 4.0 LED light; Hayward aqua logic; 2" PVC pipe 4 Jandy Valves

  8. Back To Top    #8

    Join Date
    Jul 2012
    Location
    Dumfries & Galloway, Scotland
    Posts
    296

    Re: pH won't go down

    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
    Stuart Murray
    Scotland UK
    UK NPPOC

  9. Back To Top    #9
    UnderWaterVanya's Avatar
    Join Date
    Jun 2012
    Location
    Mint Hill, NC
    Posts
    2,589

    Re: pH won't go down

    Quote Originally Posted by Stuamurr
    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.
    Dropping the TA is done with ACID as well so perhaps two birds with one...
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
    Hayward SuperPump (model ?), Polaris 380 & PB4 Booster Pump

  10. Back To Top    #10
    Smykowski's Avatar
    Join Date
    Sep 2011
    Location
    Gurnee, IL (North Suburban Chi-town)
    Posts
    3,065

    Re: pH won't go down

    Quote Originally Posted by Stuamurr
    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.
    ^^^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.

    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
    The most important article on this site - The ABCs of Pool Water Chemistry

  11. Back To Top    #11

    Re: pH won't go down

    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
    Bill
    18'X4' 7600 Gal AG
    3/4 HP Pentair Pump
    Hayward S166T 100 lb sand filter

  12. Back To Top    #12
    dmanb2b's Avatar
    Join Date
    Apr 2009
    Location
    NY
    Posts
    3,728

    Re: pH won't go down

    Quote Originally Posted by LeeM2
    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

    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.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

    Pool School, TFTestKits, Pool Calculator

  13. Back To Top    #13

    Re: pH won't go down

    Thanks all. It took more dry acid than what said on the container, but I got my pH down as well as my TA to around 80 (from 100), so it's looking pretty stable for winter closure.

    Thanks again!

  14. Back To Top    #14

    Re: pH won't go down

    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.
    Blaine

    50' x 22' 27k gal shotcrete freeform, 2hp 2 sp Pentair Whisperflo, Pool Pilot RC-52 SWCG, Pentair TR 100 sand filter, Polaris 280, 2 Pentair Intellibrite LED lights with controller, french gray plaster, Butterfield U-20 "smoke"integral colored salt finish concrete cantilever deck on one side, flagstone coping on the other.

    My pool build:
    osage-hills-pool-build-t50526.html

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •