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Thread: Trying to understand my PH rise

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    Trying to understand my PH rise

    Hi. My PH is puzzling me. We had our plaster pool drained and acid-washed in April. Since them I have been following TFP methods pretty religiously. Our pool water is beautiful, clear and clean. But...

    My PH keeps rising. This is somewhat expected with the SWG, but I was putting in two gallons of MA a week. So, I tried borates (which are great). The only effect on PH is that I now need twice as much MA to bring the level down - instead of putting in half a gallon every other day, I now put in a full gallon every other day. I don't have any fountains, slides or any other source of aeration.

    Anybody have any insights?

    FC - 5.5
    CC - 0
    PH - 7.5
    TA - 60
    CH - 425
    CYA - 80
    Borates - 50
    Salt - 3400

    ETA: fill water TA - 140, PH 8.0 (could I just be getting that much evaporation?)
    50,000 gallon plaster in-ground salt pool with two 60 sq ft DE filters, two Intellichlor IC60 SWGs, two Intelliflo VS pumps, two Whisperflo pumps, two Pentair 400K BTU NG heaters, PCC2000 in-floor cleaning system...two everything.

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    Texas Splash's Avatar
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    Re: Trying to understand my PH rise

    ETA: fill water TA - 140, PH 8.0 (could I just be getting that much evaporation?)
    Woo! That's a lot of acid. How old is your pool/plaster? One gallon of acid for 50K = about .6 of adjustment in pH. I suppose it's possible. My acid usage has increased as well by my own standards to keep-up with evaporation and fill water. That on-top of the fact you have a miniature lake for a pool. That's a good size watering hole you have there. Twice the amount of churning and aeration from water movement along with that fill TA.

    Have you ever considered a cover to help cut-back on evaporation? Pool size/shape permitting of course.
    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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    Re: Trying to understand my PH rise

    With the borates the gallon only knocks down the PH by 0.3, not 0.6 - I expected the borates to slow down the PH rise, so I would add a gallon twice a week rather than half a gallon four times a week, but that didn't happen. The plaster is 18 years old.

    The pool is an odd shape, making a cover problematic. We tried just throwing the big sheet of bubble wrap on it, but the prevailing winds just bunched it all up on one end of the pool. We spent a ton of money on solar rings, but the quality was abysmal. We had to return about half of them right away because they had air leaks. The rest failed after one season.
    50,000 gallon plaster in-ground salt pool with two 60 sq ft DE filters, two Intellichlor IC60 SWGs, two Intelliflo VS pumps, two Whisperflo pumps, two Pentair 400K BTU NG heaters, PCC2000 in-floor cleaning system...two everything.

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    Mod Squad Jimrahbe's Avatar
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    Re: Trying to understand my PH rise

    I suspect with a pool that big you also have some pretty good sized water features. What are they, and how often are they running?

    Also, where are you trying to hold your pH level? Mine stays at 7.8 for a pretty long time, but if I try to lower it to 7.2 or so, I'd have to add acid every other day.

    Jim R.
    Finished in 2015 - 17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4, IC40 SWG, 3 HP VS Pump, CCP520 Cartridge Filter.
    TF100 with SpeedStir and SampleSizer, ColorQ Pro 7, Dolphin Premier Robot Cleaner, added Screen Logic 2, added small 3 person Calder Spa.

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    Re: Trying to understand my PH rise

    50,000 gallon plaster in-ground salt pool with two 60 sq ft DE filters, two Intellichlor IC60 SWGs, two Intelliflo VS pumps, two Whisperflo pumps, two Pentair 400K BTU NG heaters, PCC2000 in-floor cleaning system...two everything.

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    JoyfulNoise's Avatar
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    Re: Trying to understand my PH rise

    What is your pH target?

    By the way, an acid washed pool will act a lot like a newly plastered pool as the acid washing etches away the calcium carbonate layer and exposes some of the calcium oxide in the deeper plaster layers. This can lead to rapid pH rise until the plaster "cures" again.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: Trying to understand my PH rise

    Quote Originally Posted by Jimrahbe View Post
    I suspect with a pool that big you also have some pretty good sized water features. What are they, and how often are they running?

    Also, where are you trying to hold your pH level? Mine stays at 7.8 for a pretty long time, but if I try to lower it to 7.2 or so, I'd have to add acid every other day.

    Jim R.
    No water features. Just a swimming hole. I've tried to see if it stabilizes at higher levels. If it does, it's higher than 8.2.

    - - - Updated - - -

    Quote Originally Posted by JoyfulNoise View Post
    What is your pH target?

    By the way, an acid washed pool will act a lot like a newly plastered pool as the acid washing etches away the calcium carbonate layer and exposes some of the calcium oxide in the deeper plaster layers. This can lead to rapid pH rise until the plaster "cures" again.
    That makes some sense. Any idea how long it might take to slow down? It's been three months so far.

    My target is anywhere from 7.5 to 7.8. When it goes over 7.8 I knock it back down to 7.5.
    50,000 gallon plaster in-ground salt pool with two 60 sq ft DE filters, two Intellichlor IC60 SWGs, two Intelliflo VS pumps, two Whisperflo pumps, two Pentair 400K BTU NG heaters, PCC2000 in-floor cleaning system...two everything.

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