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Thread: Dry Acid (pH Minus) bad for my pool?

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    daleyfolk's Avatar
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    Jul 2014
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    Dry Acid (pH Minus) bad for my pool?

    My pH rises from 7.5 up to almost 7.8 every two days. I have been adding two cups of ph Minus every other day for the last month.

    2 questions:

    1) I thought this dry acid was as safe for my vinyl pool as muriatic acid is. (As per pool school--recommended chemicals). Then I read on another thread that dry acid adds sulfates to my pool. Danger? I don't have a SWG.


    2) my TA has gone from 140 to 110 in the last month since adding the acid. That's good, right? (But the pH still rises.) Also..no aeration going on.
    17.5 K gallons (16x32) vinyl inground pool with 1 hp pump and an old Triton sand filter. >20 years old. New 2015 Rheem gas heater. TF-100 Test kit. Little red robot and a Pool Blaster Max.

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    JoyfulNoise's Avatar
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    Dry Acid (pH Minus) bad for my pool?

    Quote Originally Posted by daleyfolk View Post
    My pH rises from 7.5 up to almost 7.8 every two days. I have been adding two cups of ph Minus every other day for the last month.

    2 questions:

    1) I thought this dry acid was as safe for my vinyl pool as muriatic acid is. (As per pool school--recommended chemicals). Then I read on another thread that dry acid adds sulfates to my pool. Danger? I don't have a SWG.


    2) my TA has gone from 140 to 110 in the last month since adding the acid. That's good, right? (But the pH still rises.) Also..no aeration going on.
    1. For a vinyl pool with no SWG, it's ok to use dry acid BUT you are adding sulfates. If your pool is a seasonal type where you're draining a good deal of water at winterization and/or diluting with winter rains, then the sulfates from using dry acid are manageable.

    2. Your TA will drop with the use of acid. Your pH rise is directly tied to your high TA. Once you get your TA down near the lower limit, you should start to see a greater time period between acid additions.


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: Dry Acid (pH Minus) bad for my pool?

    Sulfates are only an issue for plaster pools if the sulfates build up to a higher level and they can be a problem in SWG pools if both calcium and sulfate levels are high. They can also be a problem for salt splash-out on porous stone or concrete hardscapes. See Sulfates why so bad? and Sulfates - what's the problem?
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    daleyfolk's Avatar
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    Re: Dry Acid (pH Minus) bad for my pool?

    Thank you for your quick response!
    17.5 K gallons (16x32) vinyl inground pool with 1 hp pump and an old Triton sand filter. >20 years old. New 2015 Rheem gas heater. TF-100 Test kit. Little red robot and a Pool Blaster Max.

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