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Thread: what is "pH Down"?

  1. #1
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    what is "pH Down"?

    I goofed...I misread a test and put WAY too much baking soda in my spa, so now I'm dealing with pH that is off the chart (8.2+ reading from the pH test in the TF100 kit)...
    so I put loads of pH Down (from SpaPure, mfgd. by Haviland) over the last 3 days, and it's still high pH.
    My question is, what is this pH Down? If it's a readily-available chemical, where can I get it? thanks
    Todd
    --------------
    Pool: 16x36, 16,800 gal., vinyl, sand filter, SWG & AquaCal Heat Pump
    Spa: Hot Springs Sovereign, 355 gal., ozone/ion
    The most helpful tool you'll ever have for your pool:
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  2. #2
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    Re: what is "pH Down"?

    I lower my PH with Muriatic Acid. My Lowes sells it in the paint department. Home Depot should have some, too.
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  3. #3
    Administrator JasonLion's Avatar
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    Re: what is "pH Down"?

    PH Down is what we tend to call dry acid, the chemical name is Sodium Bisulfate. There are no common/grocery store sources.

    You could use muriatic acid. It is less expensive and more concentrated, though the fumes can be annoying and you need to be careful with it.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  4. #4
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    Re: what is "pH Down"?

    I have a Hot Springs spa (fiberglass), and I thought I read on the forum that muriatic acid wasn't recommended for the fiberglass spas...but I do have muriatic acid for the pool. Can I use small amounts of muriatic acid in the spa?
    Todd
    --------------
    Pool: 16x36, 16,800 gal., vinyl, sand filter, SWG & AquaCal Heat Pump
    Spa: Hot Springs Sovereign, 355 gal., ozone/ion
    The most helpful tool you'll ever have for your pool:
    http://www.poolcalculator.com/

  5. #5
    Administrator JasonLion's Avatar
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    Re: what is "pH Down"?

    Yes, you can use muriatic acid in a spa, particularly an outdoor spa. However, you need to be careful when adding it to be sure that none spills directly onto the body of the spa. Also, run the jets for a minute to be sure it mixes in throughly. Indoors, the fumes can be a problem if you don't have good ventilation.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    TFP Admin. Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  6. #6
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    Re: what is "pH Down"?

    awesome, thanks...the pH down wasn't doing the trick, and I've been so tempted to enter the numbers into your calculator and use muriatic acid, so I'll (carefully) do that.
    Todd
    --------------
    Pool: 16x36, 16,800 gal., vinyl, sand filter, SWG & AquaCal Heat Pump
    Spa: Hot Springs Sovereign, 355 gal., ozone/ion
    The most helpful tool you'll ever have for your pool:
    http://www.poolcalculator.com/

  7. #7
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    Re: what is "pH Down"?

    Tnthudson, sometimes the best thing to do is to drain and refill. If your balance ever goes way out of line, it can be the best and easiest thing to do.

    Using muriatic acid is fine. You can get it in a quart, instead of a gallon, so that it is easier to handle. Open the bottle outside at a safe place, and then pour the required amount into a disposable plastic cup. Wait for the fumes to subside and then carefully walk it inside and pour it in slowly while the jets are on. Wait at least 10 minutes before retesting. Always have a plan to handle spills before handling acid.

    Also, how much baking soda did you add?

  8. #8
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    Re: what is "pH Down"?

    Hello,
    I actually finally got the darn thing leveled out pretty good by using the muriatic acid. I've used it quite a bit in my pool, so I was okay (safety-wise) with adding it. I had added some insane amount of baking soda (maybe 4 cups instead of 4 tbsp, or something like that), and I knew I may need to do a drain/refill, but fortunately it leveled out after the muriatic acid.
    I actually find a spa much harder to keep balanced than our pool; I guess it's the smaller size and therefore the smaller margin for error (?)
    thanks
    Todd
    --------------
    Pool: 16x36, 16,800 gal., vinyl, sand filter, SWG & AquaCal Heat Pump
    Spa: Hot Springs Sovereign, 355 gal., ozone/ion
    The most helpful tool you'll ever have for your pool:
    http://www.poolcalculator.com/

  9. #9
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    Re: what is "pH Down"?

    Quote Originally Posted by tnthudson
    I actually find a spa much harder to keep balanced than our pool; I guess it's the smaller size and therefore the smaller margin for error (?)
    thanks
    There are other issues in a spa; it's not just a "little pool." Bather load per gallon is much higher in a spa than in a pool, for one thing; organic contaminants are thus much higher. Also the jet action tends to cause rising pH.

    I started using muriatic in my spa, too, after some time when I used dry acid. I diluted my "spa jug" of muriatic with 9 parts water to one part MA. That way if the chart indicates that I should add .92 oz of acid, I simply need 9.2 oz of my diluted stuff. Or more likely I'll be a little conservative and use 8 oz/1 cup.

    My spa owner's manual, too, says not to use muriatic acid. I asked about it here before I tried it. Jason was most helpful (thanks again, Jason), and he was the one that suggested diluting the muriatic. Just remember, if you want to try the dilution, that you must add the ACID to the WATER and NOT the other way around!!

    Consider using borax (ie, maintaining a borate level of approximately 50 ppm) in your spa. It helps improve the water feel, discourage algae, and stabilize pH.
    ~Jules~

    My pool: INDOOR 13x27 rectangular fiberglass, built ~2001, BBB, TA-60 sand filter, Hayward two speed pump (1 hp/0.33 hp), 3/4 hp booster pump for solar heater
    Taylor K-2006 test

  10. #10
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    Re: what is "pH Down"?

    Good idea, I had thought about using borax at some point...
    thanks
    Todd
    --------------
    Pool: 16x36, 16,800 gal., vinyl, sand filter, SWG & AquaCal Heat Pump
    Spa: Hot Springs Sovereign, 355 gal., ozone/ion
    The most helpful tool you'll ever have for your pool:
    http://www.poolcalculator.com/

  11. #11
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    Re: what is "pH Down"?

    /hijack on
    I was going to ask but I Googled first. I never understood why everyone said add A to W and never W to A now I do.

    >Why is acid always added to water, and not the reverse?
    >
    >A large amount of heat is released when strong acids are mixed with water. Adding more acid releases more heat. If you >add water to acid, you form an extremely concentrated solution of acid initially. So much heat is released that the solution >may boil very violently, splashing concentrated acid out of the container! If you add acid to water, the solution that forms >is very dilute and the small amount of heat released is not enough to vaporize and spatter it. So Always Add Acid to >water, and never the reverse.
    >Author: Fred Senese senese@antoine.frostburg.edu
    /hijack off.

    Sorry back to regular programming.
    IG Vinyl liner, 21,500G sport bottom, TR-60 sand filter, 3/4 HP Whisper Flow, BBB with 12.5% Liquid Chlorine

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