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Thread: pH always high, using a ton of pH minus

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    kenmacboston's Avatar
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    pH always high, using a ton of pH minus

    I have a salt system. I check the chemicals once a week, typically:
    -alkalinity 90-100
    -calcium hardness 200-225
    -cyanuric acid 30
    -free chlorine 2.0
    -salt is 3000 PPM
    -pH 8-8.4

    I need to add at least 2-3 lbs of dry acid (sodium bisulfate) WEEKLY to get the pH down. I also use a water clarifier every week (about 8 ounces), and an algaecide (copper based) about 4 ounces a week.
    I suspect the salt is eroding the plaster as the plaster feels "pitted" and creating an alkaline water situation. Note that the pool plaster is original, at 14 years old.

    I appreciate any expert thoughts on the chemical balance and the rational behind why the pH keeps going up. The pool water is always clear and there is no algae, stains, etc.
    Ken Macumber
    18,000 Gunite, salt system, 250K BTU Hayward Heater, Waterfall, Fiber Optic Perimeter Lighting.
    20 yrs pool veteran

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    Mr Bruce's Avatar
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    Re: pH always high, using a ton of pH minus

    CYA is way low for SWG. Pool School - Chlorine / CYA Chart Muriatic Acid is way stronger/cheaper than dry acid. Your CH is way low. Your FC is way low.

    edit: Just plugged your numbers into the calculator and your CSI is 5.7
    32K gallon Plaster - 1hp Hayward 2 speed Super Pump - Hayward S200 Sand Filter - TF100XL
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    Jezza's Avatar
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    Re: pH always high, using a ton of pH minus

    Notice you have a waterfall that would be a good starting point as that creates aeration which drives your pH up
    11 000 gallons, IG, Fibreglass, Monarch Sand Filter, Davey Typhoon C100M 1HP pump, Davey Chloromatic Mc16CTO ESR SWG, Davey Pool Wall Climba Robot, Daisy Solar Cover,
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    kenmacboston's Avatar
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    Re: pH always high, using a ton of pH minus

    Thanks for the suggestions. I'll update chemicals accordingly. I cannot get muriatic acid in Massachusetts else I would (unless you know how I can get it here...) I used to use Muriatic acid and the pH stabilized better. Haven't been able to get the acid for about 8 years.
    Ken Macumber
    18,000 Gunite, salt system, 250K BTU Hayward Heater, Waterfall, Fiber Optic Perimeter Lighting.
    20 yrs pool veteran

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    Texas Splash's Avatar
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    Re: pH always high, using a ton of pH minus

    Good morning Ken. If you don't mind, I'll toss a few things back to you for consideration (some related to pH and others not) and let you see how that fits into your routine okay?
    - I would encourage you to stop using the algaecide. As you may know it's adding copper to your water which can become problematic later (staining)
    - You CH level is actually low for a SWG pool (350 min); over time this can cause the plaster to etch-away from the pool surface. This could be related to what you are seeing, so I would increase the CH soon.
    - As you know your pH is very high. It should be 7.5-7.8. Now I know why you use dry acid. But definitely lower that right away and then follow the next item ...
    - You may be able to help keep the pH lower by lowering your TA even more to about 60 ppm by following the guidance on the Pool School - Lower Total Alkalinity page. Again - using acid.
    - Your CYA is actually well below the TFP recommended 70 ppm to adequately protect the FC generated by your SWG; I would increase that right away with stabilizer
    - Your FC minimum for an SWG pool is 3, so you're actually below that right now. I would increase SWG run time/percentage, or add some regular bleach right away.

    Lots of feedback I Know. Give it a minute to process and let us know if you have any questions or concerns okay. Have a nice day.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    Catanzaro's Avatar
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    Re: pH always high, using a ton of pH minus

    Have you checked Lowe's or the Home Depot for Muriatic Acid? This is where I purchase mine. Even a business that sells concrete and materials should carry MA. Please keep us posted!
    14,700 gallons IG Pool Vinyl Liner - Octal Circulation System
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    Richard320's Avatar
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    Re: pH always high, using a ton of pH minus

    Some food for thought, since you use a lot of dry acid: Sulfates why so bad? Follow the links in post 3.

    If MA has some kind of ban on Muriatic Acid, it doesn't look like you have a long drive to a neighboring state. The stuff keeps for a long time so you can stock up.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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