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Thread: Backwashing with DE Filter

  1. Back To Top    #1

    Join Date
    May 2008
    Location
    SE Texas
    Posts
    18

    Backwashing with DE Filter

    I've read the sticky on this subject and I am still confused.

    We have a 60 sq. ft. Pentair FNS DE Filter. How much DE do I use after backwashing?

    As per the sticky I calculated the square footage of my filter and divided it by 8 which is 7.5. On my pool equipment it says one, one pound coffee can equals 7lbs of DE. So I would add just a little more than one coffee can of DE? That didn't sound correct so I called to pool supply store. She said I needed to add 12 coffee cans of DE, that REALLY doesn't sound correct.

    When I used to do this myself, prior to gettting rid of the pool service, I thought I put it 4 coffee cans, as per the Pool Builder, but I can't really remember for sure. That has been several years ago.
    18x36 Gunite w/7' spa, Whisper Flow 2HP Pump FNS DE 60 sq.ft Filter, Letro Jet Vac, Minimax Heater 400,000 BTU, Goldline Aquarite

  2. Back To Top    #2

    Join Date
    Mar 2007
    Location
    Coastalish 'down easter'
    Posts
    4,160

    Re: Backwashing with DE Filter

    Surprisingly, the lady at the pool store was right A 1 lb coffee can holds ~ 1/2 lb of DE which equals ~ 6 lbs. After backwashing, only ~80% of the initial 7.5 lbs should be added and that comes out to pretty close to 6. I will, however, reiterate that a scoop specifically for measuring DE is the best way to go! (BTW - I'm the dude who wrote the stickie, so this is the same advice )
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

  3. Back To Top    #3

    Join Date
    May 2008
    Location
    SE Texas
    Posts
    18

    Re: Backwashing with DE Filter

    Waste - wasn't questioning your method, I new there was something I wasn't doing correctly and of course I was right. I figured out that my "coffee can" is 2 lbs so I only used 7 of my coffee cans.

    I looked at two different places locally looking for the "scoop" but neither had it. I plan on ordering it online tonight.

    Thanks for your help and the "sticky".
    18x36 Gunite w/7' spa, Whisper Flow 2HP Pump FNS DE 60 sq.ft Filter, Letro Jet Vac, Minimax Heater 400,000 BTU, Goldline Aquarite

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