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Thread: Backwashing FNS 60

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    maxepr1's Avatar
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    Backwashing FNS 60

    Guy's got a pretty dumb question I guess. I would like to take a poll on how everyone is backwashing there FNS filters? Pentair's recomendation is pretty much like the one in POOL SCHOOL:
    Turn off filter
    Turn selector to Backwash
    Open air vent
    When tank is empty turn filter on
    Watch sight window until clear
    turn off filter
    Select rinse on selector
    turn filter on
    watch sight window until clear
    turn off filter
    turn selector to filter and add DE
    repeat steps 6-10 if needed

    My question is you can never drain an FNS filter due to the loction of the outlet (12 inches above the bottom) and when I open my filter to clean it most of the DE buildup is at the bottom. Also I never use the RINSE function because I never felt like it really did anything? I just go from filter to backwash to filter until no more sediment can be seen through the sightglass(usually 3 times). Then I would go ahead and add DE. And also the recomendation for 12 (1lb)coffee cans I thought was excessive for a backwash replentish, so I've been adding 7-9. Maybe 12 for a brand new start-up but I've found that after opening up the filter for cleaning there was like18-20 deep of stuck DE at the bottom of the filter that wasn't getting washed out! So I just backed off on my DE reloads. If the RINSE is not needed what is it for?
    40'x19' IG Diamond Brite 29K 4' Waterfall/Dive Rock FNS60 DE Inteliflo VS 2hp Whisperflo pumps Aqualogic(P4) SWG TF100 Tester


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    JasonLion's Avatar
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    Re: Backwashing FNS 60

    Rinse washes any DE in the multi-port or pipe between the multi-port and filter out to waste so it won't go into the pool. There is never that much DE that gets rinsed out during the rinse phase, but usually enough to just be able to notice if you skip rinse.

    You are correct that you don't need as much DE after a backwash as you need after a full clean out. If you do a really through backwash it usually needs about 80% as much DE as normal.

    DE does tend to accumulate at the bottom of the filter, though not normally as quickly as what you describe. It may be that your filter doesn't really need 12 cans of DE, even though that is what it says in the manual.
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    maxepr1's Avatar
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    Re: Backwashing FNS 60

    Yep, I figured out pretty quick Jason that I was wasting DE putting 12 scoupes in! Cut it down to 7-9. But not sure if I was doing what every body else was doing to backwash there DE filter? After reading through POOL SCHOOL and backwashing your filter I though I'd try it out! But my way still seems to work the best(filter-backwash-filter).
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    Re: Backwashing FNS 60

    I have the same filter and just broke it down to pull it out all the grids...how do i drain the rest of the water thats in the bottom and get the chunks of DE out?
    built 4/08/2000 16 x32 460 Sq FT Pool 16,000 gallons 3.5 ft 5 ft 3.5 ft sport pool

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    Re: Backwashing FNS 60

    4x4, receach under the lower PVC line there is a recess with a black 2 inch plug. That will drain the lower half of the filter. I lift the whole thing out of the filter all the grids and top plastic carrier. Get somebody to help lift it out it's going to be heavy. Pressure is the only thing holding it down. Just wiggle clockwise and cclockwise to loosen the top tube, then lift the whole thing out. Easier going in, no DE one person can just set it in place.
    40'x19' IG Diamond Brite 29K 4' Waterfall/Dive Rock FNS60 DE Inteliflo VS 2hp Whisperflo pumps Aqualogic(P4) SWG TF100 Tester


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    Re: Backwashing FNS 60

    Easiest way is to loosen the the two nuts holding it to the backwash valve, and turn the whole thing upside down.
    Then you can wash it out as well.

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    Re: Backwashing FNS 60

    perfect thanks..worked like a charm....i just finished up, looks like i put too much de in though..i had a "cup" measurement in my de container...i was think it was 12 coffee cans which are 13 oz ea for a total of 156..i put in 25 cups which is 200 oz...guess that is ok?
    built 4/08/2000 16 x32 460 Sq FT Pool 16,000 gallons 3.5 ft 5 ft 3.5 ft sport pool

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    maxepr1's Avatar
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    Re: Backwashing FNS 60

    Quote Originally Posted by 4x4tx
    perfect thanks..worked like a charm....i just finished up, looks like i put too much de in though..i had a "cup" measurement in my de container...i was think it was 12 coffee cans which are 13 oz ea for a total of 156..i put in 25 cups which is 200 oz...guess that is ok?
    Ya, I think 12 cans is for brand new start-up. For backwashing 7-9 works for me. Next time you go to break down the filter there's going to be a ton of DE in the bottom stuck between the bottom of those grids that you can't backwash out.
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    Re: Backwashing FNS 60

    Turn off filter
    Turn selector to Backwash
    Open air vent
    When tank is empty turn filter on
    Watch sight window until clear
    I prefer not to drain the filter before backwashing. If the filter is drained, then the pressure inside the grids is higher and shortens the life of the fabric.

    how do i drain the rest of the water thats in the bottom and get the chunks of DE out?
    You can use the winterizing drain or you can use a shop vac to vacuum out the remaining DE and water.

    I lift the whole thing out of the filter all the grids and top plastic carrier. Get somebody to help lift it out it's going to be heavy.
    You can remove the manifold and lift out the grids one-by-one so that you don't have to lift the whole assembly at once. Clean the individual grids and then reassemble the grid assembly.

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    maxepr1's Avatar
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    Re: Backwashing FNS 60

    Quote Originally Posted by JamesW
    Turn off filter
    Turn selector to Backwash
    Open air vent
    When tank is empty turn filter on
    Watch sight window until clear
    I prefer not to drain the filter before backwashing. If the filter is drained, then the pressure inside the grids is higher and shortens the life of the fabric.

    [quote:2n1031p4]how do i drain the rest of the water thats in the bottom and get the chunks of DE out?
    You can use the winterizing drain or you can use a shop vac to vacuum out the remaining DE and water.

    I lift the whole thing out of the filter all the grids and top plastic carrier. Get somebody to help lift it out it's going to be heavy.
    You can remove the manifold and lift out the grids one-by-one so that you don't have to lift the whole assembly at once. Clean the individual grids and then reassemble the grid assembly.[/quote:2n1031p4]

    Nah, to messy. Just lift the whole thing out hose down the trapped DE then take the wing-nuts off a remove each of the grids one at a time and wash.
    40'x19' IG Diamond Brite 29K 4' Waterfall/Dive Rock FNS60 DE Inteliflo VS 2hp Whisperflo pumps Aqualogic(P4) SWG TF100 Tester


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  11. Back To Top    #11
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    Re: Backwashing FNS 60

    Quote Originally Posted by 4x4tx
    perfect thanks..worked like a charm....i just finished up, looks like i put too much de in though..i had a "cup" measurement in my de container...i was think it was 12 coffee cans which are 13 oz ea for a total of 156..i put in 25 cups which is 200 oz...guess that is ok?
    According to Pentair the 1lb coffee can is a volume measurement. The equivalent weight measurement is 1/2 lb.

    Your filter needed 6lbs of DE and you put in 7.6 lbs. Your pressure will rise quicker than it normally would but otherwise should be o.k. Just remember what your normal starting pressure should be and clean the filter after an 8-10 pt rise.
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    Re: Backwashing FNS 60

    So for future reference, when using a "cup" to put DE powder in, what is the right amount?
    built 4/08/2000 16 x32 460 Sq FT Pool 16,000 gallons 3.5 ft 5 ft 3.5 ft sport pool

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    JasonLion's Avatar
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    Re: Backwashing FNS 60

    By far the best thing to do is to get a DE scoop. Nearly all DE scoops are 1/2 lb of DE.

    One pound of DE more or less fills a 1 lb coffee can. A 1 lb coffee can is around 5 1/2 cups. However, coffee cans are not the best thing to use because coffee cans actually vary in size somewhat these days.
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  14. Back To Top    #14

    Re: Backwashing FNS 60

    I just replaced all of my grids..for some reason I had a little trouble getting everything put back just right but thought all was good.,.when I turned my pump back on it like owed like it blew white de powder for a min back into pool... The only thing I could think of is when I put the top that mounts on top of the grids that maybe it wasn't seated all the way down on the pipe inside of the tank... Seems like I noticed it having a little gap where maybe it could have gone down more..is this allowing de to escape? I put grids in, pulled em out and pulled wholet tray out, just seemed like a like it was 100% right ...maybe grids shrink a little after use?


    built 4/08/2000 16 x32 460 Sq FT Pool 16,000 gallons 3.5 ft 5 ft 3.5 ft sport pool

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