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Thread: Trouble keeping Ph and TA down

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    Trouble keeping Ph and TA down

    My target #s are ~80 TA and ~7.2Ph.
    I'm having to add about 1 gal. of 34% MA a week to keep the Ph/TA at these levels.

    The pool was re-plastered in May, so I realize this will create a need to use more acid, but two things bother me. First, the amount of acid I'm having to add has not decreased at all since May and seems to have increased some. Second, prior to having the pool re-plastered I was still having to add (what I consider) quite a bit of acid at 1/2 gal a week. Is there something else that I should be looking at that would contribute to this rise in Ph/TA?

    Also, I didn't add acid for 4 weeks and Ph was off the charts and TA was around 400 by the time I got back on track. My SWG element would get covered in the white toothpaste stuff after just a couple of days to the point it would essentially stop producing any measurable chlorine until I hosed it off. I thought my element needed to be replaced but now that I'm adding acid regularly it seems the buildup is back to normal. What is the white gunk that builds up on the element and why does it seem to be affected by Ph/TA?
    ~18000 gal in-ground pool
    Zodiac C170S SWG
    Hayward top mount sand filter
    Hayward Pool Vac Ultra

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    Mod Squad JohnT's Avatar
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    Re: Trouble keeping Ph and TA down

    I don't think TA could go from 80 to 400 without something being added to the water. It seems that everybody in Arizona has problems with calcium in the water. Are you testing for calcium hardness?

    The acid demand for your new plaster may go on until next summer.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Trouble keeping Ph and TA down

    Quote Originally Posted by JohnT
    I don't think TA could go from 80 to 400 without something being added to the water. It seems that everybody in Arizona has problems with calcium in the water. Are you testing for calcium hardness?

    The acid demand for your new plaster may go on until next summer.
    It probably wasn't 80 to 400. It was probably more like 120 to 400. I was letting it run a little high just because I was tired of adding so much acid. As far as I know, nothing has been added to the pool. Just people swimming.

    The last time I took it to the pool store to have it tested (I don't have a kit that will do this) the CH was 380-ish. High, but not through the roof. It was about the same the time before so I don't believe it's fluctuating.

    So 1 gal a week is normal with new plaster then?
    ~18000 gal in-ground pool
    Zodiac C170S SWG
    Hayward top mount sand filter
    Hayward Pool Vac Ultra

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    mickey4paws's Avatar
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    Re: Trouble keeping Ph and TA down

    Hi Dave,
    I would recommend you get your own test kit. The TF100 is the one I have but there is also the K-2006. I have found that pool store testing can be very unreliable. Here's a link to the test kits:

    pool-school/pool_test_kit_comparison
    IG 12' x 39' - 20k Gallons - Vinyl Lined - StaRite Cristal-Flo II 26" Sand Filter - Hayward SuperPump 1 hp - Dolphin Dynamic autocleaner - Lochinvar Energyrite gas heater - Aqua Rite SWCG T-15 - TF100 Test Kit - Skimlite Duallly 9016 pole (great pole)

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    Re: Trouble keeping Ph and TA down

    I add acid at about the same rate. We have the spill over spa which drives the Ph up and the acid drives the TA down I have been keeping it has been around 60 - 80 for the last couple of months. Our TA goes up when new water is added or when the wind blows dirt into the water. I am guessing that it isn't the wind but alkalinity in the soil here.

    Our pool was plastered in May as well. No SWG I understand it that will drive your Ph up too.

    I understand about getting tired of the acid add game. There is a brand of MA at the pool store that is labled "AZ Formula" "made for the desert" leads me to believe it is just part of having a pool in these arid areas.

    I agree with mickey4paws your own test kit is important, you can not know what is going on if you are not watching the water chemistry and staying ahead of it. By the time you see it with your eyes your behind it, clearing up a mess of one kind or another.
    18,500 gallon, 16' x 38' freeform ig plaster w/ 7 ft spill over spa
    Pentair C&C+ 420 cart, Inteliflo 4 x 160 pump - new plaster on 5/5/09

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    Re: Trouble keeping Ph and TA down

    Quote Originally Posted by mickey4paws
    Hi Dave,
    I would recommend you get your own test kit. The TF100 is the one I have but there is also the K-2006. I have found that pool store testing can be very unreliable. Here's a link to the test kits:

    pool-school/pool_test_kit_comparison
    I already ordered one (TF100) and it should be here by the weekend.

    This pool has always been sparkling blue using a basic chlorine/Ph/TA kit but I'm going to start working on my brother's pool which doesn't look so good so I figured it was time to get something more than a basic kit.
    ~18000 gal in-ground pool
    Zodiac C170S SWG
    Hayward top mount sand filter
    Hayward Pool Vac Ultra

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    Re: Trouble keeping Ph and TA down

    Quote Originally Posted by camelai
    I understand about getting tired of the acid add game. There is a brand of MA at the pool store that is labled "AZ Formula" "made for the desert" leads me to believe it is just part of having a pool in these arid areas.
    Yeah, this is the stuff I get because it's the highest % I could find and the best value. I figured the "AZ Formula" was a sales gimmick, but you think they add something to it that's not in the other stuff?
    ~18000 gal in-ground pool
    Zodiac C170S SWG
    Hayward top mount sand filter
    Hayward Pool Vac Ultra

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    Join Date
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    Re: Trouble keeping Ph and TA down

    No I don't think so. I think it is just different than what the big box stores carry they have the 14.9% MA in the pool section. It is still better to add acid often than to be in the desert without a pool.
    18,500 gallon, 16' x 38' freeform ig plaster w/ 7 ft spill over spa
    Pentair C&C+ 420 cart, Inteliflo 4 x 160 pump - new plaster on 5/5/09

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