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Thread: pH and liquid chlorine

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    pH and liquid chlorine

    Hi, I'm trying to understand why controlling pH has become so difficult since switching from a stabilized granular chlorine to liquid chlorine.
    By keeping TA religiously at around 80 I barely needed a coffee cup of acid every three or four weeks with granular chlorine, but since switching to liquid chlorine I need a liter a week of acid to keep pH balanced.

    At first I thought the cyanuric acid in the granular chlorine must have been keeping the pH low enough but I'm still maintaining the stabilizer at around 30, so that can't be it. Or can it? Then I thought maybe the pool surface was seeping calcium into the water but it's a fiber glass surface now, so that can't be it either - or can it? Is itt normal to need more acid with liquid chlorine?

    Many thanks for any help on offer.
    13,000 Gallons, In Ground, Fiberglass surface , Waterco Sand Filter, glass media, use liquid chlorine.

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    Jezza's Avatar
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    Re: pH and liquid chlorine

    Adding stabilised chlorine will lower pH as it is acidic.

    Using Poolmath, adding 1kg of dichlor would bring your pH down by approximately 0.5. so your change to liquid chlorine (which is relatively pH neutral) would mean that you are not experiencing that reduction in pH any longer.

    If you bring your TA down to around 60 you might find that you can get away with adding very little acid.
    11 000 gallons, IG, Fibreglass, Monarch Sand Filter, Davey Typhoon C100M 1HP pump, Davey Chloromatic Mc16CTO ESR SWG, Davey Pool Wall Climba Robot, Daisy Solar Cover,
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    Re: pH and liquid chlorine

    Exactly. The granular chlorine was acidic, so it kept your pH down. Now that you switched to liquid chlorine, you will have to add additional acid to keep the pH in the correct range. Adding acid regularly will drop your TA over time. Keep doing what you are doing in my opinion. Your TA should continue to drop if you are having to add acid regularly.
    10,000 gallon in ground diamond brite, Circupool si30+, Hayward C900 cartridge, 1.5hp Flotec single speed pump

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    Re: pH and liquid chlorine

    I see. The dichlor will add stabilizer which in turn will increase acidity and lower pH. Okay, thank you. May I ask, how often should I add the dichlor after the initial 1kg?
    13,000 Gallons, In Ground, Fiberglass surface , Waterco Sand Filter, glass media, use liquid chlorine.

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    Mod Squad JVTrain's Avatar
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    Re: pH and liquid chlorine

    Dichlor itself is acidic, not necessarily because it adds stabilizer.

    The 1 kg number was just an example of what that amount would do to your pH level. You don't need to add this amount and likely shouldn't!

    Are you adding baking soda to religiously keep your TA at 80 ppm? If so, why? As was mentioned, allow your TA to drop to 60 ppm as you maintain pH over time and see if the pH is more stable. Your TA will go down each time you add acid.
    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
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    Re: pH and liquid chlorine

    I've bought into the myth that around 80 TA prevents pH bouncing around. I misunderstood the issue regarding dichlor. Okay... It sounds like I should do nothing, let TA drop to around 60 and see what happens to pH. Thanks.
    13,000 Gallons, In Ground, Fiberglass surface , Waterco Sand Filter, glass media, use liquid chlorine.

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    Mod Squad tim5055's Avatar
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    Re: pH and liquid chlorine

    Yup, many myths around pool care.

    As has been pointed out, every time you added the DiChlor it was the same as adding acid to the pool. Now you are adding liquid chlorine which is pH neutral and you still have a need to control rising pH. This is why more acid is needed now.

    Lowering the TA may help stabilize the pH rise, but do you have sources of areatio that may be causing pH rise? Waterfalls, sheer descents and anything else that stirs up the water causes natural pH rise.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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