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Thread: Not backwashing properly? Lots of DE remaining

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    Not backwashing properly? Lots of DE remaining

    Up here in New Hampshire closing the pool includes draining the filter completely so it won't freeze. I have a Hayward DE filter and I usually backwash it, then open it up and remove and clean the elements as well as draining it.

    This year there seemed to be a lot of DE remaining in it. Like an inch of it caked on the outside of each element.

    The filter worked fine all summer. It always starts at 15 PSI of pressure and I backwash when it has risen 10 PSI. I always backwash it until the water runs clear, then cycle it back to filter and back to backwash a few times, then add the requisite 6 lbs of DE through the skimmer. Frankly, I sometimes wonder why I don't seem to get a lot of DE collecting on the ground where the outflow is, but the filter works, so...

    So why was there so much DE remaining when I opened it? Am I not backwashing it long enough? Should I see a lot of DE on the ground when I backwash? Have I been putting too much DE in each time (rated for 6 lbs)? Is it normal to have a lot of DE caked on the elements when you open it up, even after backwashing?

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    Mod Squad Bama Rambler's Avatar
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    Re: Not backwashing properly? Lots of DE remaining

    It's probably because you're not having to backwash it as much as in the past and that you're putting a full charge of DE in after each backwash. You should only put about 80% of a fresh charge after a backwash.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: Not backwashing properly? Lots of DE remaining

    Aha! I never knew about the 80% part - I've always just put the full 6 lbs in because that's what the filter is rated at.

    So you think I'm backwashing it properly - it takes about 5 minutes for it to run clear (I hate to waste any more water than necessary). I figured it would backwash out all the DE, but apparently not?

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    Mod Squad Bama Rambler's Avatar
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    Re: Not backwashing properly? Lots of DE remaining

    I think you're doing ok. It never backwashes all the DE out and that's the reason for only refilling with 80% as much as a new fill.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Not backwashing properly? Lots of DE remaining

    Thank you!

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