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Thread: Hth salt poolcare 3-in-1 and then muriatic acid?

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    Hth salt poolcare 3-in-1 and then muriatic acid?

    Hi everyone. I haven't figured out the signature thing yet so I'll first give you my pool specs:
    Intex 16 x 48 round ultra frame pool with SWG.
    It's leveled, clear, beautiful, and horribly unbalanced.

    We filled it a few days ago, added 120 lbs of salt, and ran the filter alone for 24 hours. Then we tested--
    Yesterday, 4pm, after an unfortunate heavy rain.

    Salt test strip:
    Salt was fine: the pump had no warning indicators and a strip test confirmed that salt was in the optimum range (around 3000 for our pool.)

    Aqua chem 6-way test strip:
    Hardness was very bad: over 1000 ppm, which supposedly doesn't matter for vinyl pool.

    Total chlorine was very bad: at 0

    Free chlorine was very bad, at 0

    Ph was very bad, a brighter pink than 8.4 on the tester chart.

    TA was very bad, a blue color past the 180 on the chart.

    Stabilizer was bad, at 0.

    I added 1.5 lbs of ph down and a pound of hth 3-in-1 startup for salt pools. According to what I've read, ph down will help ph and alkalinity. The other stuff should help stabilize and contains Cyanuric acid which should help prevent the sun killing the chlorine. Then we ran swg for 6 hours and retested. Ph was slightly lower but otherwise no change. We then added nothing and ran the swg all night.

    This morning, 9am, after all night rain tested again.
    Free chlorine was a little better, in the ok range, but ph was somewhere between 7.8 and not ok.
    Everything else was still bad.

    I added a half pound of 3-in-1 and 1.5 lbs ph down and ran the SWG until now.
    3pm test
    Hardness seems to have come down a little but I'm not certain.
    Total chlorine appears to be between zero and 1 (still closer to white but I can tell it has changed)
    Ph is closer to 7.2 than 7.8 (yay!)
    TA is less blue but still not quite on the chart
    Stabilizer is still around 0.
    I added about a half lb of ph down.

    Now for the real question: we would like to go in the pool 24 hours from now. If TA and stabilizer haven't remedied at some point, can I add muriatic acid (to help the TA) and cyuranic acid to stabilize? They're chemicals so i don't know if I can put them in on to of the chems I've already put in. Also, if someone has other advice I'd love it.

    Thanks!!!

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    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Re: Hth salt poolcare 3-in-1 and then muriatic acid?

    HTH® Salt Pool Care 3-in-1 is a fairly inefficient way to add CYA. It contains sequestrant, clarifier, and CYA. Of the three you only need CYA right now, so at best the rest of it is wasted, and might conceivably cause problems.

    With very low CYA levels, you are going to lose most (all?) of your chlorine to sunlight each sunny day. Until you raise the CYA level significantly you won't be able to maintain an FC level. For a SWG we recommend CYA be between 70 and 80. However you should approach that level in a couple of steps, since it is easy to add more, but difficult to lower CYA if you overshoot.

    The hardness isn't going to come down on it's own. The only way to lower hardness is to replace water. However, the test strips are fairly unreliable, so your hardness might not actually be all that bad. You should test your fill water and see what it's hardness level is.

    Having hardness very very low is fine in a vinyl liner pool. But having hardness very high is a problem in any kind of pool.

    The best thing you could possibly do is to get a top quality test kit. Without reliable information to go on, you are just guessing about what is going on and what needs to be done.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Hth salt poolcare 3-in-1 and then muriatic acid?

    Good call, thanks. Can you recommend a test kit? I live in a small town so something I could find at a Walmart or menards would be best.

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    Re: Hth salt poolcare 3-in-1 and then muriatic acid?

    Also, the water from my sink tests the same way as far as hardness goes. I'll update after I get a better kit.

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    Re: Hth salt poolcare 3-in-1 and then muriatic acid?

    Okay, I got the best kit I could find and painstakingly followed instructions.
    Total chlorine- 2.5
    TA- 270
    Ph-7.2
    Hardness- 320
    CYA- pretty much non existant

    Now what? It doesn't make sense that my alkalinity is so high when the ph is okay.

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    Richard320's Avatar
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    Jan 2010
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    San Dimas, CA (LA County)
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    18,768

    Re: Hth salt poolcare 3-in-1 and then muriatic acid?

    Quote Originally Posted by Jen29K
    Okay, I got the best kit I could find and painstakingly followed instructions.
    Total chlorine- 2.5
    TA- 270
    Ph-7.2
    Hardness- 320
    CYA- pretty much non existant

    Now what? It doesn't make sense that my alkalinity is so high when the pH is okay.
    Sure it does. The pH will climb fairly quickly, and when you lower it with acid, you'll also lower pH.

    It might take a few days for the CYA to register; it does with plain CYA. Your SWG seems to be doing okay keeping the FC up, so stop stressing and go swimming. Note: target FC for SWG pool with zero CYA is 1 to3; up to 20 CYA is 1 to 5. You're fine.

    As long as the pool doesn't turn green, everything else is relatively easy to fix, and TA is not critical by any means.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Hth salt poolcare 3-in-1 and then muriatic acid?

    I just did a little more reading, and was tempted to go put on my suit based on my findings. Now that I've read your post, I'm for sure going to!!! Thanks!!!

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