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Thread: Constant PH drift

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    el duderino's Avatar
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    Constant PH drift

    My relatively new salt/gunite pool is experiencing MAJOR ph drift. I am putting in 2-4 cups of MA per day. I believe the major contributor is the massive amounts of aeration the pool gets from the 4 skuppers on the raised beam wall and the 26' negative edge. My analysis (per Leslie's which coincides with my own) is as follows:

    FC: 2
    CH: 250
    CYA: 30
    TA: 80
    PH: 8.0 (but has been brought down to 7.4 since test)

    My TA seems to hover in the 70-80 range, but the PH is a constant issue. I'm trying to stay on top of it rather than letting it get too high and then adding gallon plus to bring it back down. I typically add MA when the skuppers are on, as to circulate it more quickly. Also, the skuppers don't run through the filter/heater, so I figure there's less chance of damage going that route. Obviously, it adds to the aeration factor though, which I guess keeps my TA so low.

    Please help me figure out what I can do to get my PH in check. Is this to be expected or a result of new plaster (Diamond Brite)?

    Thanks!
    Our pool- (in process)
    38x15 Free Form Gunite (3.5'-8'), 26' Negative Edge and 7' Negative Edge spa with blower, Midnight Blue Diamondbrite, AquaLogic PS-8 control, Goldline Salt Chlorine Generator, 1.5hp Pentair 2 speed pumps (2), Pentair DE Filter, Pentair 400k BTU Heater, and BlackMaxPolaris 280 cleaner with Hayward booster pump

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    Mod Squad JohnT's Avatar
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    Re: Constant PH drift

    New plaster = rising pH.
    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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    el duderino's Avatar
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    Re: Constant PH drift

    How long will this continue? I've had water since March.
    Our pool- (in process)
    38x15 Free Form Gunite (3.5'-8'), 26' Negative Edge and 7' Negative Edge spa with blower, Midnight Blue Diamondbrite, AquaLogic PS-8 control, Goldline Salt Chlorine Generator, 1.5hp Pentair 2 speed pumps (2), Pentair DE Filter, Pentair 400k BTU Heater, and BlackMaxPolaris 280 cleaner with Hayward booster pump

    build diary

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    no-mas's Avatar
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    Re: Constant PH drift

    Second what John T said - can go on for 12-18 mos.


    Quote Originally Posted by el duderino
    Obviously, it adds to the aeration factor though, which I guess keeps my TA so low.
    Actually, aeration increases the pH. Adding acid and lowering the pH is what decreases the TA. Give it time, it will improve.
    18k gal inground, everbrite finish, 505 sq ft; 1.5 hp two speed whisperflow; rheem 5100ti 100k btu heat pump; 3 sheer descent falls; DE filter; swg (cell out and using trichlor for now)

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    el duderino's Avatar
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    Re: Constant PH drift

    Thanks for the replies.

    Am I better off trying to stay on top of it daily vs. weekly when it requires masses of Muriatic and big swings? I would assume the answer is yes, but I have no basis for that other than the fact that I'm keeping the water closer to "perfect" at all times rather than just for a smaller portion of the week.

    Would raising my CYA level help out here?
    Our pool- (in process)
    38x15 Free Form Gunite (3.5'-8'), 26' Negative Edge and 7' Negative Edge spa with blower, Midnight Blue Diamondbrite, AquaLogic PS-8 control, Goldline Salt Chlorine Generator, 1.5hp Pentair 2 speed pumps (2), Pentair DE Filter, Pentair 400k BTU Heater, and BlackMaxPolaris 280 cleaner with Hayward booster pump

    build diary

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    JasonLion's Avatar
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    Re: Constant PH drift

    You have two things pushing up the PH, fairly new plaster and the negative edge. A negative edge pool causes large amounts of aeration, which push up the PH. Lowering your TA level to around 60 will help, but even then the PH will still be rising any time you run the negative edge. None of this has anything to do with the CYA level.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    frustratedpoolmom's Avatar
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    Re: Constant PH drift

    You can try using trichlor pucks, they will help keep the ph in check and will raise the CYA, which you can safely go up to 50 without any issues. If you have an inline chlorinator or floater. Don't put them in the skimmer unless the pump runs 24/7.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
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    polyvue's Avatar
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    Re: Constant PH drift

    Considering the size and newness of your pool, this doesn't seem like a major shift in pH. My 2 year old pool is 14K gallons and requires the same dose of muriatic acid (2-4 Cups) -- about twice a week. I think the pH increase is partly due to SWG operation.

    Unrelated to the pH issue: Increasing CYA from it's present value of 30 (to 40-80) is probably a good idea. You'll have to increase the SWG's chlorine work by dialing up the percent a bit or extend pump operation time (to conform to FC > 5% of CYA.)

    Finally, I would hesitate to add pucks to a SWG pool.


    EDIT 9/4/2009 - Though it would seem logical to increase SWG output in order to increase chlorine production after adding cyanauric acid (CYA), in practice the opposite may be indicated. Upon increasing the CYA level in my own pool recently, I had to decrease SWG output to maintain the same levels of Free Chlorine (FC). Go figure. END OF EDIT 9/4/09 polyvue
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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    frustratedpoolmom's Avatar
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    Re: Constant PH drift

    In the first year of a plaster pool it's not uncommon to use trichlor pucks via inline chlorinator to control the PH rise, build the CYA level to where it needs to be, then switch the chlorine source to the SWG.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: Constant PH drift

    Quote Originally Posted by el duderino
    Am I better off trying to stay on top of it daily vs. weekly when it requires masses of Muriatic and big swings?
    I would be inclined to wait for it to reach 7.8, however long that takes, then bring it down to 7.2. Keeping it within those bounds shouldn't damage anything.

    Bringing up CYA is independent of all this; Pool School's Water Balance for SWGs suggests 70-80. Using trichlor will help some, I would still expect you to need MA periodically.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
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    polyvue's Avatar
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    Re: Constant PH drift

    Quote Originally Posted by frustratedpoolmom
    In the first year of a plaster pool it's not uncommon to use trichlor pucks via inline chlorinator to control the PH rise, build the CYA level to where it needs to be, then switch the chlorine source to the SWG.
    I guess that accomplishes the same thing as what I did on start up: check pH frequently, adding MA in small amounts and tweaking the SWG as needed. I add CYA directly. When CC > .2 I shock the pool with powdered trichlor (not pucks) which adds a bit to CYA, but not enough to accrete to an excessive level. Due (presumably) to splash-out, I have to add CYA every couple of months.
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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    View of spiral galaxy in Ursa Major NGC6217 - Hubble Telescope 2009

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