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Thread: SWG Calcification

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    SWG Calcification

    Firstly, thanks for these forums. I have learned almost everything I know about my pool here. Bought the house in Feb, pool just stating to go green, but with the info here and pool Calc got it back easily and have not looked back.

    But have a problem with the salt cell growing calcium rapidly and spitting it into the pool if not cleaned every week. My pool and test details follow:

    Pool plaster 44000 litres, zodiac lm2 30 SWG, manual cleaning (so far)

    Test
    TF100 not avaliable in Australia. I have been using the one from clearchoicelabs.com.au it does have a fas-dpd chlorine test and hopefully is similar to the Taylor's 2006.

    Today's results
    pH 7.8, FC 8, CC 0, TA 85, Ca 300, Cya 80, Na 4200, temp 14C

    Pool Calc says that this is balanced and is not likely to either form scale or erode the surface. As the weather warms up I will need to lower the pH as it changes more with greater swg use and these two things mean that the water would became errosive and I should bump up the Ca a bit but my eyes are saying the opposite is the problem.

    Very interested in any thoughts or advice.

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    cowboycasey's Avatar
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    Re: SWG Calcification

    Welcome to TFP

    That is a great kit.. Your CSI is at -0.31 and that is a good place for the SWG.. As the temp rises your CSI will rise... I know my SWG has some scale on it but very little and when it changes polarity it comes right off (not in chunks)

    Has it always done this or is this a new install, with your temp below 60 degrees (14 C) it is probably not working at the level it will when the temp rises.
    Pool: Intex 16x32 15000 gal, 2 speed 340042, Pentair CC320 Filter, CircuPool SJ45 Salt System, Intermatic PE653RC; Hot Tub: 650 Gal SWG Megachlor
    links: pool school * Recommended-Levels * SLAM * CYA chart * Test kits * How To Post Pictures * Poolmath * OCLT ** Support your website if we helped you :) **

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    Re: SWG Calcification

    Welcome to TFP!

    Make sure that the system is switching the polarity, I believe the manual should let you know how to do this.

    You can add 50ppm borates which will help with preventing some of the scaling.

    Lower the pH to 7.6 and see if the scale still forms as fast.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

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    Mod Squad pooldv's Avatar
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    Re: SWG Calcification

    Shifting CSI to the negative side should help with scaling. Between -0.3 and 0 is best.
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    Re: SWG Calcification

    Quote Originally Posted by pooldv View Post
    Shifting CSI to the negative side should help with scaling. Between -0.3 and 0 is best.
    His number is already -.31 so there is something else going on here. My first guess is the pH is higher than 7.8 since it is very difficult to read pH above 7.8.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

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    Mod Squad pooldv's Avatar
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    Re: SWG Calcification

    Casey's post says 0.31, not -0.31. Yes, pH could be above 7.8
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    Re: SWG Calcification

    Quote Originally Posted by pooldv View Post
    Casey's post says 0.31, not -0.31. Yes, pH could be above 7.8
    Early morning post it was -0.31 .... sorry about that, changed...
    Pool: Intex 16x32 15000 gal, 2 speed 340042, Pentair CC320 Filter, CircuPool SJ45 Salt System, Intermatic PE653RC; Hot Tub: 650 Gal SWG Megachlor
    links: pool school * Recommended-Levels * SLAM * CYA chart * Test kits * How To Post Pictures * Poolmath * OCLT ** Support your website if we helped you :) **

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    Re: SWG Calcification

    Quote Originally Posted by cowboycasey View Post
    Has it always done this or is this a new install, with your temp below 60 degrees (14 C) it is probably not working at the level it will when the temp rises.
    It has done it ever since I got the water relatively in balance after moving into the house. (Largely thanks to lurking on this forum.) When I got the pool it was just starting to go green. The pump was running for 14 hours a day, the chemistry was something like FC 1, CC 1, pH 8.2, TA 100, CH 150, CYA <30, Salt 1000.

    Since I got the calcium up to a level recommended for a plaster pool I have had trouble with the SWG throwing off chunks of calcium into the pool. In the cool weather it is producing enough chlorine with the pump running 1.5 hours per day. BTW there is no scaling anywhere else in the pool.

    Quote Originally Posted by ping View Post
    Welcome to TFP!

    Make sure that the system is switching the polarity, I believe the manual should let you know how to do this.

    You can add 50ppm borates which will help with preventing some of the scaling.

    Lower the pH to 7.6 and see if the scale still forms as fast.
    I have put a multimeter on it and have not detected a polarity change. The manual says that it should be self cleaning. Do you know how often it should change? Is it 50% each way or just a brief period in the reverse direction?

    I am planning on adding borates but was waiting until I sorted out this issue. Maybe I'll give it a try.

    There does not seem to be a difference at a pH of 7.6.


    Quote Originally Posted by ping View Post
    His number is already -.31 so there is something else going on here. My first guess is the pH is higher than 7.8 since it is very difficult to read pH above 7.8.
    I think my pH is 7.8 as when I add the amount of HCl acid recommended by pool math to lower it to 7.6 the pH does go to 7.6. I have thought of lowering the pH more to try and fix this problem, however, with the pool currently quite cold, my CSI is correct with a pH of 7.8. I was planning on lowering the pH as the pool warms up as this seems to be the easiest parameter to change that contributes to CSI. With the current chemistry and temperature, at a pH of 7.6 the CSI is -0.5 and at 7.5 it is -0.6.

    Thank you everyone for your help,

    GQ
    ​GeoQuack
    Melbourne, Australia. Plaster pool 44,000 Litre (11,625 US gallons), 2 HP 1 speed pump, Zodiac LM3-40 SWG, Zodiac CX20 robotic cleaner, PoolSkim, solar heating, sand filter, clearchoicelabs.com.au test kit (TF100 or taylors not available in Australia), big eucalypt that drops infinate leaves, gum nuts, pollen and sticks into pool

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    Re: SWG Calcification

    To avoid the issues you are having during the cold water months it might be best to turn off the SWG and use liquid chlorine instead. You will only have to add once a week at most I'm guessing. Once the water warms up you will then be able to drop the pH and you shouldn't have issues with the scaling.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

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    Re: SWG Calcification

    I have added HCl to drop the pH to 7.6 and the problem seems to have improved. How much of a problem will having a CSI of -0.5 be?

    Also, does anyone know how often and for how long the polarity of the salt cell is supposed to change?
    ​GeoQuack
    Melbourne, Australia. Plaster pool 44,000 Litre (11,625 US gallons), 2 HP 1 speed pump, Zodiac LM3-40 SWG, Zodiac CX20 robotic cleaner, PoolSkim, solar heating, sand filter, clearchoicelabs.com.au test kit (TF100 or taylors not available in Australia), big eucalypt that drops infinate leaves, gum nuts, pollen and sticks into pool

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    Mod Squad pooldv's Avatar
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    Re: SWG Calcification

    That is a little too aggressive over the long term, months to years. Increase CH to 350 to compensate.
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    Re: SWG Calcification

    As an update, there was something wrong with the salt cell or control system. The transformer for driving the salt cell in the controller box died. Because it wasn't that much more expensive to replace the whole system (new control box and salt cell), I did that. I haven't changed the pool chemistry, but the new system is not getting any scale build up on it.

    Thanks for your help everyone.
    ​GeoQuack
    Melbourne, Australia. Plaster pool 44,000 Litre (11,625 US gallons), 2 HP 1 speed pump, Zodiac LM3-40 SWG, Zodiac CX20 robotic cleaner, PoolSkim, solar heating, sand filter, clearchoicelabs.com.au test kit (TF100 or taylors not available in Australia), big eucalypt that drops infinate leaves, gum nuts, pollen and sticks into pool

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