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Thread: Why does it take so much MA to keep PH under control?

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    Why does it take so much MA to keep PH under control?

    Just curious to know if anybody else with a SWCG has to go through 1.5 gallons of MA a month to keep PH at 7.6-7.8 range...my numbers are consistently as follows:

    TC=3.0-4.0 range
    FC=3.0-4.0 ranhe
    TA=70-80 range
    PH=7.6-7.8 range
    CYA=50 (jusr recently increased from 30)
    CH=500
    Borates=30-35 range

    I'm running my pump 4 hours a day (will increase to 6 as we reach 80º-85º water temp) and set the SWCG at 25%

    Any comments appreciated..
    Inground with 7x7 spa (spillover)
    20k gal plaster (sunstone)
    pentair 3/4 hp (filter), 1 hp (spa), 1/2 hp (features)
    cartridge filter
    SWCG IC-40
    Polaris Platinum (with booster)

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    Mod Squad JohnT's Avatar
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    Re: Why does it take so much MA to keep PH under control?

    Constantly rising pH is a side effect of the SWCG. If you raise your CYA, you'll need less run time which will reduce the pH rise.

    How old is your plaster?
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Why does it take so much MA to keep PH under control?

    Thanks JohnT...the plaster is 9 months..I suppose as it finally cures, balancing should be easier...not that it's a problem now, just that it seems like a whole lot of MA...
    Inground with 7x7 spa (spillover)
    20k gal plaster (sunstone)
    pentair 3/4 hp (filter), 1 hp (spa), 1/2 hp (features)
    cartridge filter
    SWCG IC-40
    Polaris Platinum (with booster)

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    Mod Squad JohnT's Avatar
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    Re: Why does it take so much MA to keep PH under control?

    Yeah, new plaster plus SWCG equals a lot of MA.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    JasonLion's Avatar
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    Re: Why does it take so much MA to keep PH under control?

    A fair bit of that PH increase is from the plaster curing. You can reduce the PH increase from the SWG by raising CYA to 80, lowering the percentage till your FC level is correct again, and allowing TA to go down to 60.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Why does it take so much MA to keep PH under control?

    ok, but increasing CYA won't imply having to increase chlorine output to counter CYA/Chlorine bonding, thus having to run the SWCG at higher rates, thus raising PH again?...tricky, isn't it?
    Inground with 7x7 spa (spillover)
    20k gal plaster (sunstone)
    pentair 3/4 hp (filter), 1 hp (spa), 1/2 hp (features)
    cartridge filter
    SWCG IC-40
    Polaris Platinum (with booster)

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    Mod Squad Bama Rambler's Avatar
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    Re: Why does it take so much MA to keep PH under control?

    It's kinda strange how it works. Increasing CYA reduces the amount of FC that gets burned off by the sun thereby reducing the amount of FC you have to replace which means less FC the SWCG has to produce to keep the FC at the proper level so the less runtime means less outgassing and the less it drives the pH up. Whew! That was a mouthful!
    Dave J. TFP Moderator
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    Mod Squad JohnT's Avatar
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    Re: Why does it take so much MA to keep PH under control?

    Quote Originally Posted by serge
    ok, but increasing CYA won't imply having to increase chlorine output to counter CYA/Chlorine bonding, thus having to run the SWCG at higher rates, thus raising PH again?...tricky, isn't it?
    That relationship doesn't hold for SWCG pools. Check out the Chlorine CYA Chart and note the difference between SWCG and non-SWCG pool levels.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Why does it take so much MA to keep PH under control?

    Woao...I'll just keep my MA routine for now, until plaster cures. Then I will try to reach a new equilibrium...thank you all for your comments
    Inground with 7x7 spa (spillover)
    20k gal plaster (sunstone)
    pentair 3/4 hp (filter), 1 hp (spa), 1/2 hp (features)
    cartridge filter
    SWCG IC-40
    Polaris Platinum (with booster)

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    Re: Why does it take so much MA to keep PH under control?

    I use about 2 gallons of MA per month to keep my PH/TA in check.

    In central TX we have very high TA so all my fill water is constantly adding TA to the pool that then makes the PH swing worse, so more MA to counter the increased TA from fill water and the cycle continues.

    So I average 2 gallons per month.
    15,500 gal, inground gunite pool with 7 ft spa, 2 speed pump 2hp/.33hp, 3/4 hp booster pump, Intermatic P1353 timer, AutoPilot SC-48, Sand filter with ZeoBest, Heater, that I never use . . .

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    Re: Why does it take so much MA to keep PH under control?

    I spent the first two months with our new pool adding acid manually. After lots of research on this site, last weekend I installed a CAT-1000 PH system and Stenner Pump/Tank combo.

    Now we're cruising along at 7.5 with a lot less stress about PH swings in between testing.
    18 x 28 with 8x8 Spa with Vanishing Edge Dam wall, Pentair 4 x 160 & 2 Whisperflo, Badu Swimjet SuperSport, Pentair 400Kbtu Minimax, 80sqft DE CAT 1000 PH Controller with Stenner Pump/Tank combo

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    Re: Why does it take so much MA to keep PH under control?

    That sounds like a good idea Jcourt...what was the cost(if you don't mind my asking)?
    Inground with 7x7 spa (spillover)
    20k gal plaster (sunstone)
    pentair 3/4 hp (filter), 1 hp (spa), 1/2 hp (features)
    cartridge filter
    SWCG IC-40
    Polaris Platinum (with booster)

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    Re: Why does it take so much MA to keep PH under control?

    I used a lot of MA the first year and still quite a bit the second year. I keep my TA low, at about 60-70 and my PH stays fairly stable now. Once we start using the slide it will start creeping again.
    Gary
    21k gal SW, IG Gunite PebbleSheen, 1HP Jandy, Jandy 340 filter, Polaris 280, 17' fiberglass slide w/ 2HP pump.

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    Re: Why does it take so much MA to keep PH under control?

    Serge - all in about $1,300 if you install it yourself.
    18 x 28 with 8x8 Spa with Vanishing Edge Dam wall, Pentair 4 x 160 & 2 Whisperflo, Badu Swimjet SuperSport, Pentair 400Kbtu Minimax, 80sqft DE CAT 1000 PH Controller with Stenner Pump/Tank combo

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