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Thread: PH for SWG

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    PH for SWG

    I am just starting my second year with a brand new pool. Chlorinated via SWG. The pool is 13,500 gallons and last year I was going through a gallon of muriatic acid per week. I've been open for 5 days now and it looks like the trend continues.....lots of muriatic acid. Is this expected? What are your SWG experiences from a PH standpoint? Are you too adding acid everyday?

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    JasonLion's Avatar
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    Re: PH for SWG

    Rapid PH increases with a SWG are almost always caused by having your TA too high. You want TA down around 60 to minimize the PH increases.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: PH for SWG

    60 will be a struggle due to all of the acid I put in. Maybe I'll start alternating days between acid and baking soda treatments

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    Re: PH for SWG

    What is your TA now? Can you post a full set of results? Following TFP's recs for a vinyl liner with a SWG my ph stays really stable once everything is balanced. I don't think I've used a gallon of acid in the last four years.

    I think what Jason is saying is that if your TA is high and is causing the ph issue once you get the TA down it won't be a struggle as you say. Your PH will stabilize and you won't be putting all that acid in.
    18' x 36' saltwater inground vinyl pool

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    Propbndr's Avatar
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    Re: PH for SWG

    I would skip the baking soda and use acid addition and aeration to allow the TA to come down. It may take time but, it will balance out.
    Steve
    32 X 16 inground, 17260 gallons, Vinyl Liner, Triton II TR-60 filter,
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    Re: PH for SWG

    TA should be between 60 and 90 with a SWCG system. I'm currently at 80 and my PH is steady.
    20X36 IG vinyl (18,000 gal), 3 sheer descents, Max-Flo 1.5hp VS 2300, Aquarite T15 SWG, C3030 filter, 250,000 BTU heater, Sharkvac XL (Hayward equip)

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    ned8377's Avatar
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    Re: PH for SWG

    Quote Originally Posted by Propbndr View Post
    I would skip the baking soda and use acid addition and aeration to allow the TA to come down. It may take time but, it will balance out.
    Aeration is a very important concept and is really the only way to get the TA down and let the PH rise without raising the TA also. Once the TA is down to say 80 aeration causes CO2 to outgas and the PH to go up. This can occur in a couple of hours if there are five 10 year olds in the pool. There are other ways to aerate such as if you have a waterfall etc. To be clear, this is something that would occur naturally over a couple of days if the 10 year olds never showed up or there is no waterfall. It is a matter of equilibrium. Once the PH is too low due to lowering the the TA and PH with acid, carbon dioxide equilibrium will occur and the PH will naturally move back up to around 7.5 whether through aeration or if you just wait. Even pool stores will tell you to correct the TA first but you don't have to buy their chemicals. They probably won't tell you about aeration though.

    You don't say if you have a vinyl pool but if you do, you don't want to lower the PH much below 7.0. So, get your TA down in increments by not drastically lowering the PH. You may have to do this several times but once the TA is around 80 your PH should be stabilizing and not rising as fast.
    True L 45,000 gal Hayward IG vinyl pool. Hayward Tristar 2.40 THP; 1.5 FRHP/1.60 SF. Hayward Model # S310T2 Sand Filter. Aqua Rite T-15. Aqua Comfort 154,000 BTU Heat Pump. TF-100

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    Re: PH for SWG

    Thanks everyone. I did a test tonight and my alkalinity was at 110. I threw in about 4lbs of baking soda tonight. My pool is an aggregate plaster finish. I will retest tomorrow.

    I did a pH test tonight also and it was 7.5. That's a first meaning I have higher readings at night as I add acid in the morning. I only opened the pool a week ago, so who knows, maybe this second year will be different meaning less acid demand.

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    Mod Squad pooldv's Avatar
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    Re: PH for SWG

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    Re: PH for SWG

    Quote Originally Posted by dubele View Post
    Thanks everyone. I did a test tonight and my alkalinity was at 110. I threw in about 4lbs of baking soda tonight. My pool is an aggregate plaster finish. I will retest tomorrow.

    I did a pH test tonight also and it was 7.5. That's a first meaning I have higher readings at night as I add acid in the morning. I only opened the pool a week ago, so who knows, maybe this second year will be different meaning less acid demand.
    Why are you adding baking soda?

    Baking soda raises TA and that is exactly opposite of what you want. Please read this, ABC's of Pool Water Chemistry.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
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    Mod Squad pooldv's Avatar
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    Re: PH for SWG

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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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