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Thread: Adjusting pH

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    Join Date
    May 2014
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    Adjusting pH

    Hello,
    Here are my test results for today.
    pH 8.0 (btwn 7.8 and 8.2)
    FC 6.5
    CC 0.5
    TA 90
    CH 275
    CYA 70

    The pH has trended up from 7.2 to 8ish over the last 5 weeks. I think that means I need to add some muriatic acid, correct? What should I target for pH? I was thinking 7.5 but in reading posts on the forum, I've seen Richard mention targeting 7.2 in a few places to help eliminate calcium scaling. I have no idea if scaling is a problem at this point in my pool. I'm also told I probably only have a 3-5 years left before it needs to be resurfaced so I'm not all that worried at this point about a little scaling. (The pool is new to me this year.)

    Thanks in advance for any help.
    Peter
    18K gallon, IG plaster, cartridge filter, refinished around 7 years ago, attached spa, natural gas heater

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    steveg_nh's Avatar
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    Re: Adjusting pH

    I would target PH of around 7.4. That may it gives you some breathing room before you treat again. I like ph around 7.5-7.6. And yes, MA is ideal in most cases, especially if you have a SWG. But you are plaster, so I'm not 100% sure. Careful with hit though, if you haven't used it before. Did you read up on PH in pool school? It will tell you everything you need to know...great info in there.
    24'x40' 25k gal Imperial Mountain Pond IGP, full 28 mil VynAll Ocean Breakers liner. All Hayward system: 140k BTU HeatPro heat pump, 3/4HP single speed TriStar 2" Pump, DE6020 filter, AquaPlus Automation/Salt Chlorination, remote controls, ColorLogic 4.0 lighting. Polaris 280 w/PB4-60 BP. TF100 & K1766 test kits. Rinox Palazzo pavers and Spherik coping. Pool installed 9/2013, project completed 6/16/14.

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    Re: Adjusting pH

    I have read Pool School, pretty much every word. It talks about target ranges and how to adjust, but doesn't discuss when you are adjusting, where to target. Seeing as the level has been slowly trending up, I'm guessing aiming for the low end of the range is ideal. I have also seen mention of 7.2 as a target, so just trying to get a sense of what my ideal target should be.
    18K gallon, IG plaster, cartridge filter, refinished around 7 years ago, attached spa, natural gas heater

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    Mod Squad JVTrain's Avatar
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    Re: Adjusting pH

    Plug in all those test results into Pool Math. If you're concerned about scaling and your plaster, once you have all the numbers in the Now column, look at the CSI number toward the bottom. With your numbers plugged in, I have a current CSI of 0.31 which means some potential for scaling. If you put in a pH of 7.4 in the Target column, the CSI is then -0.24 which is balanced, not quite corrosive to plaster. If you change the Target pH to 7.2 the CSI changes to -0.42, potential to be corrosive to plaster. Anything 0.6 or greater for CSI will cause scaling, anything less than -0.6 will cause corrosion. It's a grey possibility area at > 0.4 and < -0.4.

    Tinkering with Pool Math is very helpful and dare I say it... FUN!
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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    mrcarcrazy's Avatar
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    Re: Adjusting pH

    Quote Originally Posted by JVTrain View Post
    Plug in all those test results into Pool Math. If you're concerned about scaling and your plaster, once you have all the numbers in the Now column, look at the CSI number toward the bottom. With your numbers plugged in, I have a current CSI of 0.31 which means some potential for scaling. If you put in a pH of 7.4 in the Target column, the CSI is then -0.24 which is balanced, not quite corrosive to plaster. If you change the Target pH to 7.2 the CSI changes to -0.42, potential to be corrosive to plaster. Anything 0.6 or greater for CSI will cause scaling, anything less than -0.6 will cause corrosion. It's a grey possibility area at > 0.4 and < -0.4.

    Tinkering with Pool Math is very helpful and dare I say it... FUN!
    At least I'm not the only one that finds it entertaining to play with.
    IG gunite/plaster pool/spa Started 1/17/14, Plastered 5/16/14
    Size: 12'-21'x39' free form, depth ranging from 4' to 7, attached 6 person spa with spillover.
    Equipment: Whisperflo 2hp pump, Pentair 30" sand filter, Pentair Mastertemp 400k BTU heater, 1hp Whisperflo for waterfalls, and a blower for spa floor

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    Mod Squad JVTrain's Avatar
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    Re: Adjusting pH

    Quote Originally Posted by mrcarcrazy View Post
    At least I'm not the only one that finds it entertaining to play with.
    Haha. We're both in the club.


    Also seriously... the grey area for potential scaling and corrosion is actually > 0.3 and < -0.3 Apparently I'm a nerd who can type faster than my brain can think.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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