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Thread: Understanding shocking as well as adding DE to a sand filter

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    Understanding shocking as well as adding DE to a sand filter

    My current values are:
    FC 6
    CC 0
    CYA 35
    pH 7.2
    TA 90

    My water is not very clear. I can see the bottom and it appears swimmable, but it just doesn't look quite right. I wanted to shock and read that I needed to take my FC up to 15 and keep it there. How long do I keep it there?
    In the mean time, I added a half cup of DE to my sand filter. This caused the pressure to go up by 1 to 2 lbs of pressure after 20 min. After 3 hours it is up to 35psi. The normal psi is 22-24psi. I have backwashed and added the DE three times. Each time it goes up 1 to 2 lbs in the first 20 minutes but ends up rising 10-15 psi within 3 hours. Do I have too much DE or is it simply doing its job?

    My pool is near a lot of blowing dirt from crops nearby. The dirt settles to the bottom and is then filtered by an infloor system pushing debris to the sand filter.
    1) 25,000 gallons
    2) Sand Filter 24"
    3) Inground
    4) Plaster
    5) 2 hp pump on 2'' pipe

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    Join Date
    Feb 2008
    Location
    Denton, TX
    Posts
    5,061

    Re: Understanding shocking as well as adding DE to a sand fi

    I would try less DE. That's a significant pressure rise.

    When shocking, you continue the process until your water clears, you have 0.5 or less CC, and your FC holds to within 1 ppm overnight. The higher the FC is when you shock, the sooner you will finish.

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