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Thread: Consistent High pH

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    Consistent High pH

    I seem to be having trouble with keeping my pH in the 7.4 to 7.6 range... I've been adding about 30 to 50 ounces of dry acid every three weeks or so to keep the pH from going over 8. Is that normal? And what might be driving it up? Could the Pebble Tec finish be causing it? All of my other parameters have been nice and stable ever since I did the water change out (to address a high CYA problem I inherited from the previous owner) over two months ago. Here are the most recent readings:

    FC 3
    CC 0
    pH 7.8
    TA 90
    CH 225
    CYA 60
    Temp 58F

    Thoughts?
    26K gal, IG Pebble Tec, 2 HP Jandy Pump, 420 sqft filter (Durex Triton C&C Plus with 4 PCC105 Pleatco filters), Barracuda G3 Vacuum, build date unknown, using Taylor K-2006 Test Kit.

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    Patrick_B's Avatar
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    Re: Consistent High pH

    Yes, I'm guessing your fill water TA is fairly high?

    Have you considered using liquid MA (Muriatic Acid) instead? It's advisable, because it's more economical and your dry acid is like adding Sulphates.

    Lastly, that isn't much acid addition to be honest with you.
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    Re: Consistent High pH

    Regardless of the cause, I would do what it takes to keep my pH below 8.0 at all times

    Is there a reason you are using dry acid over muriatic?

    How long has this been happening? Your pool is over 2 years old at least, right?
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    Mod Squad jblizzle's Avatar
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    Re: Consistent High pH

    Do you have any water features / spa?
    Do you have a SWG?
    Both of those can drive the pH up.
    Plaster < 1 year old can as well ... does not sound like the case here.
    Also the colder water will tend to drive the pH up.

    How are you chlorinating?
    Your TA is a little higher than we might suggest, the pH would not rise as fast if it was lower.

    I recommend you start using muriatic acid so you are not building up sulphates in the water by using the dry acid.
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    Mod Squad woodyp's Avatar
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    Re: Consistent High pH

    That is a reasonable amount of acid to add every 3 weeks or so for a 26k pool I think.
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    Richard320's Avatar
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    Re: Consistent High pH

    Quote Originally Posted by woodyp View Post
    That is a reasonable amount of acid to add every 3 weeks or so for a 26k pool I think.
    I'd say it's low. 50 oz of dry acid is a bit over a quart of liquid. I add that much to a 16K pool every week during the summer!

    JPhresh, test your tap water. I'll bet it has high TA.
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    Re: Consistent High pH

    Typical dry acid is a bit weaker, and the cost gets you. It would be a slow build at your rate, but it's still best not to build up Sulphates in the pool. One part of our philosophy is minimizing side effects, and dry acid falls in that category.
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    Re: Consistent High pH

    As you add acid, your TA will usually drop, unless you're adding a lot of high TA fill water. If you're adding bicarb to raise the TA back up, that will cause the ph to continue to rise. The pH rises some on addition of the bicarb and then it rises more over time as the high level of bicarb in the water converts into carbon dioxide and off gasses.

    Try keeping your TA at about 60 and the pH at about 7.7 to 7.8.

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    Re: Consistent High pH

    Wow -- thanks for all the responses! I will definitely switch over to muriatic acid. I was using dry acid because I inherited a large supply, but that's pretty much gone now. I'm chlorinating using liquid chlorine (10%).

    Otherwise, I don't think I have any of the conditions suggested above that might cause higher pH. The pool was installed long ago and the last refinish was done over five years ago. No water features. Not sure what a SWG is, though!

    I tested my tap water before I did the change-out and the TA is 90, which matches what I now have in the pool, of course. Sounds like the TA will drop as I add acid, but if there's something else I can/should do to bring down the TA, please advise!

    Otherwise, it seems my chemistry is behaving normally and I just need to stay the course of monitoring and adjusting pH as needed.
    26K gal, IG Pebble Tec, 2 HP Jandy Pump, 420 sqft filter (Durex Triton C&C Plus with 4 PCC105 Pleatco filters), Barracuda G3 Vacuum, build date unknown, using Taylor K-2006 Test Kit.

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    Re: Consistent High pH

    Add enough liquid acid to drop your pH down to 7.2. Aerate your pool back up to 7.6 pH. Rinse and repeat. Your TA will drop nicely.
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    Mod Squad jblizzle's Avatar
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    Re: Consistent High pH

    Quote Originally Posted by elwood58 View Post
    Add enough liquid acid to drop your pH down to 7.2. Aerate your pool back up to 7.6 pH. Rinse and repeat. Your TA will drop nicely.
    You only need to do this if you are actively trying to lower the TA. In this case with a TA of 90ppm, I would just maintain the pH in the 7s and let the TA do as it will.
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