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Thread: my numbers & question about adding muriatic acid

  1. Back To Top    #1

    Join Date
    Jul 2009
    Fort Wayne, IN

    my numbers & question about adding muriatic acid

    the numbers are in and they don't look good

    FC 8.5
    CC 0
    pH 8.2
    T/A 230
    CYA 15

    The bad news.
    I have been battling (and losing) the T/A. Plus, we had a bunch of kids over the weekend and today I noticed algae at the bottom of the pool I am confused how I can see algae, but my CC comes up 0. To add fuel to the fire, I had been adding water due to a leak that is finally found and resolved and got off track with the CYA. So, I thought I had been shocking my pool, but found I have been barely keeping up with the required amount of bleach.

    The good news.
    The people on this wonderful site have taught me so much that I actually know what is wrong and have the ability to fix it.

    Today I plan to add 45 oz stabilizer and enough bleach to get it and keep it at shock level. I need to add muriatic acid, but I'm unsure of how much. If I already start with a high pH, and need to lower it anyway, does the calculator take this into account? Wondering if I should add 47 oz of acid, or 121 oz of acid.

    Also, it seems to me that right now everything is off balance. It seems like so many things affect so many other things. Like shocking it with give a false pH reading, and the T/A affects the pH as well. Poor pH, it can't get a break

    Shower me with your wonderful advice!
    Theresa and/or Gary

    Complete DIY: 20x40' rectangle. Resin walls, vinyl lined. 33000 gallons. Full width steps. 8' deep. Diving board, slide. Hayward pro series super pump, sand filter. Raypack 336K BTU heater. Main drain, 2 skimmers, 3 returns, 2 amerilite lights with quick change lens Aquamatic auto cover and a partridge in a pear tree.
    Breaking our backs in the hopes that one of our six kids will care for us when we are old ;)

  2. Back To Top    #2
    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: my numbers & question about adding muriatic acid

    I get a totally different number for MA when I punch your numbers into Pool Calculator. Just plug in now and target and see what it says. If the acid number looks too high, put in half. You can always add more later.

    You will use a lot of acid getting that TA down. You'll add a quart or whatever, pH will drop nicely, then through aeration/circulation, pH will go back up but TA will have dropped a tiny amount. Repeat until you're beyond sure you've done something wrong. You probably haven't. It will come down in time.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

  3. Back To Top    #3
    Mod Squad woodyp's Avatar
    Join Date
    Apr 2010
    East Texas

    Re: my numbers & question about adding muriatic acid

    If your pool needs shocking to clear up the algae problem...........WAIT.......until it is cleared before raising your CYA/stabilizer level any. It will just require a higher level of free chlorine if you do.
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
    2 Speed Hayward Power-Flo Matrix 85 g.p.m. 22" 250lb. sand filter hard plumbed
    Pool Rover Jr., Pool Blaster Max, Diver Dave TF100 Test Kit/Speed Stir
    Margaritaville Frozen Concoction Maker, Liqour Chiller, & Drink Mixer & Party Tub----Collect 'um all!

  4. Back To Top    #4

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    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: my numbers & question about adding muriatic acid


    Your pool is easily correctable.

    1. Lower your pH to around 7.2-7.4 or so. Use muriatic acid.

    2. Disregard the resultant TA for now. It will come down when you add acid but disregard'll adjust it later.

    3. As soon as you get pH down, shock the pool according to the article in Pool School..."How to Shock Your Pool".

    If you added the 45 0z of CYA, shock as if your CYA was 50 (20+ppm), or shock at 10-12ppm if you didn't add it.

    4. As soon as you have completed the shock process.....

    1. Your pool water is sparkling
    2. Your CC's are .5ppm or less
    3. You can hold your FC overnight without losing more than 1ppm.

    Then post back a full set of test results and we'll help you adjust anything that needs it.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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