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Thread: bleach raising pH rapidly

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    bleach raising pH rapidly

    As a new pool owner five years ago, I started using bleach after stumbling across this very helpful forum. However, I found I was going through a gallon of muriatic acid every week to keep the pH down. I noticed after switching to trichlor tablets (when I left the house for two weeks and had no one to watch my pool) that my pH had kept an even 7.5 since I'd left. I found that in fact my pH never varied as long as I'd use trichlor. The only problem of course is the buildup of CYA--which seems to climb almost precisely 50ppm per six months. Draining my pool every 18 months is not something I find that economical, (and seems wasteful), so after draining my pool completely last July, I used trichlor till last January (when CYA reached 50ppm) and went back to bleach. Sure enough, with an alkalinity of 70, starting at 7.2 pH, I notice my pH rises 0.2 to 0.3 four days after adding 121 fl. oz. of 8.25% bleach. So, just 363 oz later, I'm having to dump half a gallon of muriatic acid to get pH down to 7.5. Of course my alkalinity goes down slightly, so I have to dump in baking soda. Sometimes I wonder if replacing 28,000 gallons of water is more economical in the end--definitely a lot less trouble using trichlor.

    The reason I bring this up is because when I've searched the forums here, I keep seeing that bleach isn't supposed to raise pH much over-all--especially with a low TA, yet that's not been my experience at all; so I'm curious if I'm doing something wrong or missing some key element? Is it ok to drive my TA much lower than 70 to help buffer the effects of bleach?

    Thanks in advance for any advice...

    Steve
    28,000 gallons, IG, plaster, Hayward 48SF DE filter, Hayward Max Flo VS, Pool built 1975, TF-100 test kit, Polaris 380

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    Mod Squad jblizzle's Avatar
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    Re: bleach raising pH rapidly

    Welcome to TFP!!!

    The bleach is basically pH neutral, slight rise when added, but the pH drops back down as the chlorine is consumed.

    Try letting the TA go down a little more, like 60ppm.

    Do you have any water features in your pool?
    What is the pH of your top off water?
    Jason, TFP Moderator
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    Patrick_B's Avatar
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    Re: bleach raising pH rapidly

    Yes, one thing you are missing is that using Pucks drives the pH down, so when you remove them from use, you no longer have that helping to push the pH down.

    The net reaction/conversion of bleach winds up being neutral, even though in neat form bleach pH is high.
    TFP Moderator
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    Re: bleach raising pH rapidly

    A simple thing like pointing your returns down instead of up toward the surface will prevent PH from raising due to aeration.
    Viking Maui 2300g fiberglass in ground pool in a screened room with polycarbonate roof. 45gpm pump with sand filter manually chlorinated. Entire pool water can cycle in 51 minutes. Jacuzzi 336g hot tub with ozonator, manually chlorinated. TF 100 test kit with speed stir. Fungi pronounced Fun Guy, I'm Jim

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    Richard320's Avatar
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    Re: bleach raising pH rapidly

    Welcome!

    It's not bleach raising pH, it's pucks not lowering it anymore. Trichlor is very acidic. Plug all your numbers into poolmath and then scroll down to Effects of Adding Chemicals and see what each 8 oz puck will do to pH.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    Mod Squad Bama Rambler's Avatar
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    Re: bleach raising pH rapidly

    It won't hurt anything to let your TA come down to 60 ppm or even close to 50 if that's what it takes to stabilize your pH.
    Dave J. TFP Moderator
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    Re: bleach raising pH rapidly

    Wow, thanks for the "welcomes" and all the responses, folks....

    Jblizzle and Fungi, I don't have any water features, nor do the return jets break the surface. The're not much splashing around (by would-be-swimmers) either, as temps just haven't gotten high enough so far this year to splash around in the pool for very long. I don't know off hand what my tap water is pH wise, but will test when I get home. It's been raining like crazy here lately (seems like the monsoons have migrated to Texas), but apparently I'm not getting enough "acid-rain". :P

    Bama Rambler, I'll try taking my TA down to 50, and see if that keeps my pool's acid addiction down...

    Thanks again for the ideas, everyone!
    28,000 gallons, IG, plaster, Hayward 48SF DE filter, Hayward Max Flo VS, Pool built 1975, TF-100 test kit, Polaris 380

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    Re: bleach raising pH rapidly

    You have been given some great advise. I just wanted to say welcome to TFP!
    Lisa
    Intex AG vinyl 15' x 48" 4,300 gallons due to skimmer install, Krystal Clear SF pump combo 2800 GPH, Krystal Clear SWG, Pool Blaster Max vacuum, Hayward thru the wall skimmer, TF 100 test kit with speed stir, K 1766 Taylor salt test, My SLAM Process

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    Re: bleach raising pH rapidly

    Thank you Azgirl71.

    Jblizzle, the water I top the pool off with is 7.5 pH; but I haven't had to in the last two months.
    28,000 gallons, IG, plaster, Hayward 48SF DE filter, Hayward Max Flo VS, Pool built 1975, TF-100 test kit, Polaris 380

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