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Thread: scale buildup in cells of intellichlor IC40, needs frequent acid wash

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    scale buildup in cells of intellichlor IC40, needs frequent acid wash

    After 4 years of working with little need for cleaning, my intellichlor IC40 now requires frequent (about every 1-to-2 weeks) acid wash else it will not produce chlorine. The reason is pretty obvious, it builds up significant amount of minerals between the plates, near the top and bottom edges.

    This photo shows the scale buildup view from top https://flic.kr/p/pa9cbU
    and this one from bottom https://flic.kr/p/pa8Qu2

    These two photos are after washing with acid: https://flic.kr/p/ppB29s and https://flic.kr/p/prCT5e

    Note that the most central plates in the cell, where most buildup occurs, have been eaten away (best seen in photos after washing ).

    Where do I start looking for the reason for this. Chemistry (my PH is fine I keep it 7.5-7.8)? Chlorinator (rotten cells)? Any help is welcome.

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    Re: scale buildup in cells of intellichlor IC40, needs frequent acid wash

    A full set of test results, including water temperature, would help us help you.

  3. Back To Top    #3

    Join Date
    Jun 2014
    Location
    Roseville, CA
    Posts
    341

    Re: scale buildup in cells of intellichlor IC40, needs frequent acid wash

    You are probably high on one thing or another. Your test results will help zero in on your issue.

    I was able to find a hose nozzle with sufficient pressure to clean my cell without acid. Bed Bath & Beyond sells a "as seen on TV" type nozzel that may also do the trick.

    I've been able to avoid acid of all types since conventional wisdom is Muraitic acid is bad and vinegar is safe but slow.
    SWG: CircuPool (May 2014) SI30+Plus; 3000ppm seems ideal;
    My Ideal Specs:
    FC 5; PH 7.4-7.6; TA 90; CH 350; CYA 75; = SI ~ 0.19
    14,000 gal, in ground, plaster, Cartridge filter, Borates
    TAYLOR K - 2006

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    Re: scale buildup in cells of intellichlor IC40, needs frequent acid wash

    Quote Originally Posted by JamesW View Post
    A full set of test results, including water temperature, would help us help you.
    Here we go, from my local pool store:
    FAC: 5
    TAC: 5
    pH: 7.5
    TA: 100
    AA: 100
    CYA: 20
    Calcium Hardness: 400
    salt: 3400
    phosphates: 100

    The chlorine seems high but that's intentional: I ran it at high all day yesterday since it had dropped low since I had postponed cleaning the salt-cell a bit.

    I have had the problem for the better part of the year, during which the water temperature has changed from low 60s to low 80s (pools stay open during winter in Southern California)
    Looking forward to your advice
    B
    Last edited by bgrinstein; 09-29-2014 at 09:03 PM. Reason: clarification

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    Re: scale buildup in cells of intellichlor IC40, needs frequent acid wash

    Your current numbers don't indicate a big risk for scaling. However, with your TA so high, I would suspect that the pH frequently gets high, which could lead to scaling.

    The roughness on the plates increases the risk of scaling because it creates a surface more conducive to holding scale.

    If the plates are damaged in such a way as to prevent cell reversing, then buildup would not be reversed as designed.

    Also, if the cell is after a heater, then the water would periodically be hotter, which increases the CSI and increases the risk of scaling.

    I would suggest lowering the TA to about 60 and increasing the CYA to about 60.

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    Re: scale buildup in cells of intellichlor IC40, needs frequent acid wash

    Quote Originally Posted by JamesW View Post
    Your current numbers don't indicate a big risk for scaling. However, with your TA so high, I would suspect that the pH frequently gets high, which could lead to scaling.

    The roughness on the plates increases the risk of scaling because it creates a surface more conducive to holding scale.

    If the plates are damaged in such a way as to prevent cell reversing, then buildup would not be reversed as designed.

    Also, if the cell is after a heater, then the water would periodically be hotter, which increases the CSI and increases the risk of scaling.

    I would suggest lowering the TA to about 60 and increasing the CYA to about 60.
    How can I tell if the plates are damaged in such a way as to prevent cell reversing? Also, if they are damaged, can I replaced the damaged plates only (as opposed to replacing the whole chlorinator, which is a hefty expense)?

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    Join Date
    Sep 2014
    Location
    Bakersfield, CA
    Posts
    155

    Re: scale buildup in cells of intellichlor IC40, needs frequent acid wash

    Quote Originally Posted by bgrinstein View Post
    Here we go, from my local pool store:
    FAC: 5
    TAC: 5
    pH: 7.5
    TA: 100
    AA: 100
    CYA: 20
    Calcium Hardness: 400
    salt: 3400
    phosphates: 100
    If you read thru the posts on the "Just Getting Started" forum you will find that test results from pool stores are often worthless, and will lead you to make decisions that are usually wrong and expensive.

    Buy a decent test kit and find out for yourself if your water is truly balanced and your CSI is is where it should be.
    Cheers, Peter
    20,000 gal, 52'x17' kidney shaped IG, Pebble Tec, IntelliPro P6E6VS4H-209L pump. Intellichlor IC40 SWG.
    300 sf Sta-Rite System 3 cartridge filter. Poolvergnuegen 4-wheel suction pool cleaner. TF-100 test kit.

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