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Thread: Alkalinity

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    Alkalinity

    Pool not holding chlorine, ph was 7.6, alk was 110 and we have been shocking the heck out of the water. Now.... the alkalinity is 160 and the ph has dropped to 7.2, and adding soda ash is not helping... what can I do to maintain the ph while lowering the alk???

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    Mod Squad tim5055's Avatar
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    Re: Alkalinity

    Welcome to TFP

    Soda ash is not helping because soda ash will raise both the PH and TA levels

    Check out the article Lower Total Alkalinity in Pool School

    But, TA is the one parameter we tend not to fuss around with. How do your other water numbers look? TA will not hinder your pools ability to hold chlorine. You need to be looking at other issues if you have a high chlorine demand. Low CYA/Stabilizer can allow FC to be burned off by teh sun and things growing in the water will cause high chlorine demand.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Richard320's Avatar
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    Re: Alkalinity

    Welcome!

    Aerating the water - pointing the returns up, running spas, waterfalls, or slides, devising some sort of sprayer, any of those will work to raise pH.

    The big question is - what are you using to "shock the heck" out of the pool? If the label says dichlor or trichlor or the long versions of those chemical names, you're not just adding chlorine, you're adding cyanuric acid (stabilizer) and acid, which lowers the pH. It can also render the chlorine ineffectual if it gets too high. The majority of the pools that need to be drained are because of CYA buildup.

    What are the rest of your test results, and where did they come from?
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    Re: Alkalinity

    I don't have the CYA from today, but it has been running at near perfect levels until we had a storm roll through last night and now the spike in TA. We are using tri-chlor tabs in the pool, but turned off the chlorinator to try to shock it with liquid chlorine. We were told to shock every thirty minutes, test and shock again until it was holding chlorine then we could wait 60 minutes and test again. If we add the MA to bring down TA, can we still shock the pool?

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    Mod Squad tim5055's Avatar
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    Re: Alkalinity

    Quote Originally Posted by Chieppamom View Post
    I don't have the CYA from today, but it has been running at near perfect levels until we had a storm roll through last night and now the spike in TA. We are using tri-chlor tabs in the pool, but turned off the chlorinator to try to shock it with liquid chlorine. We were told to shock every thirty minutes, test and shock again until it was holding chlorine then we could wait 60 minutes and test again. If we add the MA to bring down TA, can we still shock the pool?
    Can I assume the pool store is giving you this advice? What are you testing with?

    How big is your pool and how much shock are you using each time (volume and %)

    The basis of the TFP system is accurate testing and only adding what your pool needs, in the correct amount when it needs it. Without a correct CYA reading you cannot determine how much chlorine to use. Use too little chlorine and it does no good. Use too much chlorine and it can damage your equipment or liner if you have one.

    Thus, we do not "shock" our pools, we follow the SLAM Process when there is a problem.

    But to follow our system you will need to pick up one of the recommended test kits. To effectively practice the TFPC methods, the FAS/DPD chlorine test is essential. All the kits on the list contain that test while very few other kits do. The kits sold at the pool store generally won't won't cut it, but be careful pool store employees are known to say “it's the same thing”. Generally it's not!

    Not much credence is given to pool store testing around here. While you would think that a "professional" would be the best, unfortunately in most cases it is quite the opposite. Between employees who blindly trust the word of chemical sales representatives and high school kids working in the pool store for the summer you end up with poor results from their testing. In my case two different pool stores told me my CYA was "fine", around 70 or 80. When I tested myself I found it over 200.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    JasonLion's Avatar
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    Re: Alkalinity

    You should not try to lower TA at the same time you are shocking or SLAMing. High FC levels make the PH test unreliable.

    If you need to raise PH you can either aerate (which will raise PH without affecting TA) or use borax (which will mostly just raise PH but will also raise TA just a little bit).
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    Re: Alkalinity

    Taylor kits are used for testing... and we were going to add only what was needed when it started registering FC. but we haven't done it yet, as the TA problem arose. the pool is 24,000 gals and we know to use only what is needed.... I have a state inspection in two days and wanted to see if it was okay to add the MA and still do the shock demand.

    - - - Updated - - -

    That's what I needed to know... so first deal with the TA... then we can deal with the SLAMing! thank you!

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    Mod Squad pooldv's Avatar
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    Re: Alkalinity

    Welcome to TFP!

    No, SLAM and then deal with TA after everything else is OK. Everything else is chlorine first, PH second, CYA third, TA and CH last.

    Are you following the SLAMing Your Pool process? Did you adjust PH to 7.2-7.5 before you started? If yes then you are fine to continue the SLAM.


    Here are some intro Pool School articles to read while you are SLAMing
    TFPC for Beginners
    ABC's of Pool Water Chemistry

    Here are the Recommended Levels for your pool.
    Here are the Recommended Pool Chemicals
    Use PoolMath to figure out how much to add.
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    Re: Alkalinity

    State inspection? Is this for a private pool or a public pool?

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