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Thread: Is a gallon of muriatic acid per week ok?

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    Is a gallon of muriatic acid per week ok?

    I've been using about a gallon of muriatic acid per week to control pH and I'm just wondering if this is ok. I measure pH everyday, but I usually add the acid once per week, right after I go through my full weekly battery of tests on Saturday.

    Saturday morning, I'll get done with my testing and almost consistently find the pH up around 8.2. I'll add a gallon of muriatic acid, and test again a few hours later to find it at 7.2. The reason I add once per week is because I really like to limit my exposure to the stuff and only want to deal with it once per week.

    However, I'm just wondering if it seems normal for my size IGP to be using a gallon per week.

    FC = 5
    CC = 0
    TC = 5
    pH = 7.5
    TA = 100
    CH = 250
    CYA = 40
    Salt = 2000
    Borate = 31.6
    26k Gal. 18' x 38' Gunite/White Plaster Roman style in-ground pool, straight Clorox bleach sanitizer, DE filter, TF-100 Test Kit, Taylor Salt Test Kit, Borate Drop test

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    Re: Is a gallon of muriatic acid per week ok?

    If it's a new pool that's normal--at least that's about what I used for the first few months.

    Now I use about a quart a week, but I have a SWG and lots of aeration.
    9,200 gal. Gunite Luna Quartz French Grey pool with spill over spa, two fountains on tanning ledge (rarely used)
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    epro05's Avatar
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    Re: Is a gallon of muriatic acid per week ok?

    PoolMath say that for each gallon of 31.45% acid in a 23k gal pool at TA=100, TA will decrease by 22. Just wondering if you are seeing a this level of TA decrease each week? Also wondering what TA your fill water is?
    27,500 gallon in ground gunite/plaster (1995). Attached Spa with fountain, spillway, and 2 lion heads streaming into the pool. Hayward pump and AO Smith UST1152 1.5 hp motor (single speed). Hayward 60 sq ft DE Filter (Model DE-6000). Kreepy Krauly cleaner.

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    Re: Is a gallon of muriatic acid per week ok?

    Quote Originally Posted by HouTex View Post
    If it's a new pool that's normal--at least that's about what I used for the first few months.

    Now I use about a quart a week, but I have a SWG and lots of aeration.
    Hi HouTex. Yep, I forgot to mention this is a brand new pool finished mid-June of this year. I was thinking the rise in pH might have something to do with the new plaster, but wasn't sure.

    Quote Originally Posted by epro05 View Post
    PoolMath say that for each gallon of 31.45% acid in a 23k gal pool at TA=100, TA will decrease by 22. Just wondering if you are seeing a this level of TA decrease each week? Also wondering what TA your fill water is?
    epro5: I have not tried measuring TA directly after dumping in the gallon of muriatic acid. I've only measured pH about three hours after and then remeasured TA the following week with the rest of my testing battery.
    I'm going to try testing TA directly after adding muriatic acid this coming weekend though and see what drop I get. I'm also interested in the TA of my fill water. I'll try that as well.
    26k Gal. 18' x 38' Gunite/White Plaster Roman style in-ground pool, straight Clorox bleach sanitizer, DE filter, TF-100 Test Kit, Taylor Salt Test Kit, Borate Drop test

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    Re: Is a gallon of muriatic acid per week ok?

    You should be adding the acid more often, do not let the pH rise above 7.8 as you are risking scaling when the pH is above 7.8. With time the acid demand will slow down as the plaster cures.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
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    Re: Is a gallon of muriatic acid per week ok?

    Quote Originally Posted by ping View Post
    You should be adding the acid more often, do not let the pH rise above 7.8 as you are risking scaling when the pH is above 7.8. With time the acid demand will slow down as the plaster cures.


    I was going to say that. Smaller additions several times a week are much better on the pool and equipment than huge fluctuations once a week.
    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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    Re: Is a gallon of muriatic acid per week ok?

    Quote Originally Posted by ping View Post
    You should be adding the acid more often, do not let the pH rise above 7.8 as you are risking scaling when the pH is above 7.8. With time the acid demand will slow down as the plaster cures.
    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
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    Re: Is a gallon of muriatic acid per week ok?

    Quote Originally Posted by tim5055 View Post


    I was going to say that. Smaller additions several times a week are much better on the pool and equipment than huge fluctuations once a week.
    Sound advice!
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    Re: Is a gallon of muriatic acid per week ok?

    I needed to lower PH so I bought some muriatic acid and started reading up on how to use it, I was frankly scared after reading the instructions people posted about using it, went to HD and got some PH down, don't care if it costs a couple of extra bucks

    so I have 2 jugs of MA in North Atlanta (dunwoody) if anyone is interested
    Tallman Monterey (fiberglass), 16'x33', 11500 gallons, 480 sq/ft, Depth: 3' - 5' 6", Salt Water, TF-100, Pentair pump, sand filter, Easy Touch Control System, SWG

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    Re: Is a gallon of muriatic acid per week ok?

    That's my pool's diet with new plaster, but my pool is twice as big.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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    Re: Is a gallon of muriatic acid per week ok?

    Quote Originally Posted by WWells View Post
    I needed to lower PH so I bought some muriatic acid and started reading up on how to use it, I was frankly scared after reading the instructions people posted about using it, went to HD and got some PH down, don't care if it costs a couple of extra bucks
    You are better off with the muriatic acid since the PH down add sulfates in the water and in long run you might regret it. The hydrochloric acid is normally found even in human stomac so do not hesitate to use it. It is better for the pool and cheaper too.
    South of France inground rectangular 17k pool - ruber membrane. Sliding dome, black thermal blanket covering 75% of the pool surface. Aqualux 3/4Hp pump, glass media sand filter, Zodillac robot, 110W UV-c lamp, Hayward brominator, Caliente 12kW heat pump.

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    Re: Is a gallon of muriatic acid per week ok?

    I bet my comment is one of the ones you are referring to. I use and like 31.45 because it minimizes the volume I have to use, but yes, it's strong stuff.

    I believe Home Depot near me carries a weaker one. Lowe's also has a second bottle I have never read the label of. Look for a more dilute concentration than 31.45...like 15ish.
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