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Thread: Test results after partial drain / refill

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    Test results after partial drain / refill

    Ok, finally got around to draining / refilling to fix CYA problem. Also ordered the TF-100 test kit to get more accurate results. I'm pretty happy where it came out at, I think I can work with these numbers:

    FC: 3
    CC: .5
    pH: 7.8
    TA: 100
    CH: 350
    CYA: 60

    So, according to what I've learned here, CYA is on the high side but from here on out I'll be using liquid chlorine so I think I can just let it drift down, it was 100+ before so I'm pretty happy to see it at least in acceptable range. The first thing I need to do is get FC up, according to the chart it needs to be around 7, and it's currently below the minimum (of course I guess that might be expected considering I just filled). I didn't have a CH test prior to the drain / refill, but the fact it's at 350 AFTER replacing half the water tells me it was pretty darned high before.

    What other recommendations do you guys have for me with these results? Do I need to SLAM the pool since I just replaced so much water?

    Thanks again, you guys are the best.
    25k gal in ground w/spa - Gunite
    2HP WhisperFlow Pump - Pentair 320 Cartridge Filter
    H-400 Hayward Heater - 2HP Q.T. Blower
    Kreepy Krauly - Compool LX 3400 Controls

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    JasonLion's Avatar
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    Re: Test results after partial drain / refill

    You are in reasonably good shape. The main thing you need to do is to get your FC level up. I recommend aiming a little higher than normal for the first day or two, just to be sure you don't lose control of things. Then let it drift back down to our recommended levels and settle into your routine.

    Longer term you are probably going to want to lower the TA level, but I doubt there is any rush on that. If PH drifts up annoyingly quickly, then attack TA more aggressively. But most likely it will be fine dealing with it over several weeks or a couple of months. The simple and slower approach is simply to lower PH to 7.2 each time it gets to 7.8 for as long as TA is higher than our recommendations. Over time that will bring the TA level down.

    Finally, you will want to get a CH reading on your fill water, to get an idea if managing CH levels is going to be an on-going issue or not.
    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: Test results after partial drain / refill

    Do I need to SLAM the pool since I just replaced so much water?
    Only if your water condition is poor. If your water is really clear, you are just fine. Nice work on getting your chemistry in shape!
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Test results after partial drain / refill

    Ok, so I performed the overnight loss test just to see where I was at. FC was at 8 before bed last night, and 6.5 first thing this morning, so I decided to go ahead and SLAM just to keep ahead of any problems that might crop up, I just don't want to take any chances.

    But what is bothering me a little more right now is the pH. I took it down to 7.2 yesterday evening, and tonight it was already back up to 7.8+. I put in enough muriatic acid to bring it back down to 7.2, but I'm not sure if I should just keep doing that or address the issue in some other manner.
    25k gal in ground w/spa - Gunite
    2HP WhisperFlow Pump - Pentair 320 Cartridge Filter
    H-400 Hayward Heater - 2HP Q.T. Blower
    Kreepy Krauly - Compool LX 3400 Controls

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    Smykowski's Avatar
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    Re: Test results after partial drain / refill

    Try bringing the pH to 7.5 and see what happens. Some pools naturally find 7.7 or 7.8 and just stay there. My pool's happy place is 7.6 with a TA of 90, so you'll have to play a little and see where it settles.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
    The most important article on this site - The ABCs of Pool Water Chemistry

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    Re: Test results after partial drain / refill

    Sure I'll give it a try, thanks for the advice
    25k gal in ground w/spa - Gunite
    2HP WhisperFlow Pump - Pentair 320 Cartridge Filter
    H-400 Hayward Heater - 2HP Q.T. Blower
    Kreepy Krauly - Compool LX 3400 Controls

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    Re: Test results after partial drain / refill

    If you are SLAMing, ignore the pH until you finish.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Test results after partial drain / refill

    Ok, I've been testing pH just to see where it was, it hit 7.5 on it's own this morning and hasn't changed. I guess the SLAM is over, I only lost 1ppm FC last night and this evening CC was 0, water is crystal clear and 75 degrees... I'm about ready for a swim!

    I'm so glad I found this forum, not only is it easy and rewarding to maintain your pool on your own, but I'm finding it enjoyable... In the same way I find mowing the lawn enjoyable.
    Last edited by jjmac; 04-07-2015 at 10:39 PM. Reason: got my days mixed up, I tested pH this morning not yesterday morning
    25k gal in ground w/spa - Gunite
    2HP WhisperFlow Pump - Pentair 320 Cartridge Filter
    H-400 Hayward Heater - 2HP Q.T. Blower
    Kreepy Krauly - Compool LX 3400 Controls

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