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Thread: Safest way to add muriatic acid?

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    Safest way to add muriatic acid?

    After my first accurate water test I needed to lower the pH, so I got a gallon jug of muriatic acid. Pool Math said to add 18 oz. The directions on the jug say to partially submerge the jug and pour with the spout an inch or two above the water surface, I suppose to avoid splashing it in your face. But then it says to estimate the amount since it will be impossible to measure accurately.

    Does anyone one have a better way to do this? Can you safely pour this stuff into a household measuring cup? Do some of you keep dedicated measuring cups for exactly this purpose? (My wife will not approve of me running into the kitchen to grab a measuring cup from the cabinet to measure my highly toxic acid, I'm sure!)

    BTW, I did estimate the amount, rested the water about 12 hours later and found my pH had gone from 8.2 to 7.2 overnight, so I overshot my goal by a little bit.
    22K 16'x40' inground fiberglass pool, Hayward Pro Series High Rate Sand filter, Hayward dual speed 2 hp Super II Pump, Hayward AquaRite SWG, Raypak 400K btu propane heater, Dolphin Supreme M400 cleaning robot, CoverPool auto cover. Also stand-alone Sundance Hawthorne 430 gallon hot tub.

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    pabeader's Avatar
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    Re: Safest way to add muriatic acid?

    I pour into a quart measure that I got free from the hardware store. The fumes don't bother me at all. I'm not considered normal here. Or anywhere, now that I think about it.

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    JoyfulNoise's Avatar
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    Re: Safest way to add muriatic acid?

    I have used a plastic painters quart which is graduated in 4 oz increments to measure from the gallon jug I have. I do it over the pool water and make sure I'm up-wind so the fumes don't hit my nose. Doing this secondary container measure obviously introduces a safety issue in that it increases the chance of spillage or splashing. I consider myself to be fairly comfortable around most of the pool chemicals out there but that's because I worked in a corporate R&D lab environment for many years and have extensive OSHA-based chemical handling and safety training. In other words, I'm a cowboy -



    Just be safe and wear proper eye protection (standard safety glasses will be just fine). And don't freak out from the fumes...while they are gross and acidic smelling, a quick-whiff/brief exposure to them is not anything to worry about. Believe me, the human smell recoil reflex will protect you just fine.


    Matt
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    Mod Squad pooldv's Avatar
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    Re: Safest way to add muriatic acid?

    I estimate my addition 1/4 bottle, 1/2 bottle, etc. Get upwind of the bottle. Float the bottle in the water above a pool return so that the bottle opening is facing the direction of the water flow from the pool return and about 1 inch above the water. Pour slowly so that the MA is taken away by the water flow.
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    ozdiver's Avatar
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    Re: Safest way to add muriatic acid?

    1. Don't wear your favorite concert T-shirt
    2. Pour carefully into your chosen measuring container (That you save for MA addition and not Bleach)
    3. Don't panic if you splash a little, you have a very large plunge tank right in front of you. Use it if things get out of hand.
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    Richard320's Avatar
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    Re: Safest way to add muriatic acid?

    I just stand upwind and extend my arm out as far as I can and let it rip. Your pool is big enough and the pH range is wide enough that you can guesstimate close enough. If you want to be precise, the way I used to be, you squat upwind and pour the acid into a measuring cup held over the pool and as soon as you measure, empty the cup. Then rinse it in the pool.

    The less handling, the fewer chances for a spill.
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    Mod Squad jblizzle's Avatar
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    Re: Safest way to add muriatic acid?

    In a 22k pool, I would not think you need to be more accurate than 1/4 bottle. And I have no explanation for how around ~20oz could lower the pH from 8.2 to 7.2 unless your TA is way too low or one of the test was not right.
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    Re: Safest way to add muriatic acid?

    Hi jblizzle,

    My pool is in the last phases of construction so it's only about 60% full. That means the acid was acting on only about 13,000 gallons. I know people don't like overly wordy posts on the forum so I left that out as I didn't think it was germane to my question, which was about how to safely add the acid, not how much to add.

    The only test I have for pH with the TF-100 is color-matching, unless I'm missing something. (I found it odd that the directions say not to record that and the color-matching FC test, but then there's not a more accurate pH test available later in the process.) So maybe my pH estimate numbers were a little off, but I don't think by much.

    My TA is about 50, so that is too low. I plan to work on that once the pool is full. As soon as the PB turned the pump and filter on, my first priority was to get pH and FC in a decent range so we could jump in and enjoy the water.

    I wanted to be more accurate than 1/4 bottle because PoolMath suggested 18 oz. for 13K of water and 1/4 of a bottle is 32 oz. That seemed like a big difference to me, especially for my first time trying this. I'm glad that you are confident with approximating, but I'm new at this, so next time I think I'll measure.
    22K 16'x40' inground fiberglass pool, Hayward Pro Series High Rate Sand filter, Hayward dual speed 2 hp Super II Pump, Hayward AquaRite SWG, Raypak 400K btu propane heater, Dolphin Supreme M400 cleaning robot, CoverPool auto cover. Also stand-alone Sundance Hawthorne 430 gallon hot tub.

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    Mod Squad pooldv's Avatar
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    Re: Safest way to add muriatic acid?

    18oz would be 1/8th bottle. Don't raise your TA too much or too fast. Wait to see how your PH behaves and if it stabilizes. Raise it 10ppm at a time and check your PH daily for a week or so. As soon as your PH remains stable leave the TA where it is.
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