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Thread: Should I backwash my DE filter after shocking?

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    Should I backwash my DE filter after shocking?

    I'm in the midst of shocking my pool for mustard algae. The pressure on my DE pump has not risen at all, and the water never got cloudy, even after brushing. Should I backwash anyway, to try and get rid of as many algae spores and such as possible?

    Thanks.

    Kelley
    Kelleyaynn
    21,000 gallon (+ or -) in-ground plaster pool with Nautilus DE filter, 1 hp pump, and Zodiac G4 automatic vacuum.

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    Re: Should I backwash my DE filter after shocking?

    I would not. My assumption is that the mustard algae will be killed regardless of whether it is in the filter or the pool. I think the only time to backwash a DE filter is when the pressure goes over the manufacturer's specified level. On my DE filter, even when I backwash there is still a LOT of DE left in the filter. Backwashing does not leave you with a crystal clear set of grids, it will likely still be pretty caked with DE, so even if you backwash you will have a LOT of old DE left in there.
    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

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    Re: Should I backwash my DE filter after shocking?

    Thanks, you reply makes sense to me.

    Kelley
    Kelleyaynn
    21,000 gallon (+ or -) in-ground plaster pool with Nautilus DE filter, 1 hp pump, and Zodiac G4 automatic vacuum.

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    Mod Squad jblizzle's Avatar
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    Re: Should I backwash my DE filter after shocking?

    I do not know what the "manufacturer's specified level" is for backwashing ... how can they give a number without knowing your pump, plumbing and head loss?

    Just wanted to point out that we recommend backwashing when the pressure goes up 20-25% of the clean pressure reading. (The old 10psi pressure raise is not a good rule of thumb).
    Jason, TFP Moderator
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