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Thread: FNS Plus Poor Backwashing

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    FNS Plus Poor Backwashing

    Hi All,

    Newbie to the forum.

    I take care of my parents inground pool (16x32 cement wall vinyl liner). Several years ago I had to replace the 25 year old Lomart DE filter (disc elements with a handle so they could be spun during backwash). I ended up getting the Purex Triton FNS Plus 36. This filter has never backwashed cleanly. I let it backwash for a long time, turn it off and on, go back and forth between backwash / filter, ... but always seems to have pressure creep during the season. I disassemble it at the end of every season and am always amazed at the amount of DE that seems to remain in the filter.

    Anyone have a good routine for this filter?

    I think that old Lomart was a better filter, I can't believe they went out of business. One of these days I'm going to try and build a Lomart copy!

    Thanks!

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    no-mas's Avatar
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    Re: FNS Plus Poor Backwashing

    Welcome to the forum.

    I have the same filter - well, the pentair version. Every other time I backwash, I remove the lid, open the drain at the bottom of the filter tank, and hose down the grids. It's not quite as good as a full breakdown and clean, but it gets much more DE out that would otherwise have remained behind after backwashing.
    18k gal inground, everbrite finish, 505 sq ft; 1.5 hp two speed whisperflow; rheem 5100ti 100k btu heat pump; 3 sheer descent falls; DE filter; swg (cell out and using trichlor for now)

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    Re: FNS Plus Poor Backwashing

    Bummer. Thats too much work for my dad. I usually only open / close the pool since I'm a few states away.

    I did notice on the label they recommend disassembly biannually. Geesh, that old filter could go several seasons before opening it up.

    Thanks

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    Heckpools's Avatar
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    Re: FNS Plus Poor Backwashing

    instead of going from backwash to filter, try backwashing, then to rinse and then back to backwash..( do this a few times) also, when you add the new de powder, add 1 pound LESS then it says too.. when you backwash not ALL of the de will come out, so if you continue to add the amount it says too, by the end of the season u'll have a caked up mess!
    [center:3gj9kdnn]Matt Heck
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    Re: FNS Plus Poor Backwashing

    hello all -
    I think I have the same model for my pool.
    The system is about 9 years old.
    Over time, it has become difficult or impossible to read the labels on the controls.
    There are 6 settings that go around clockwise. The handle goes around and locks into notches at:
    12 o'clock
    2 o'clock
    4 o'clock
    6 o'clock
    8 o'clock
    10 o'clock
    I am sorry for the long post, I'm having some trouble explaining this.
    Basically what I need to know what these settings are for the filter system.
    Here are the settings that I do know:
    12 o'clock is "BACKWASH"
    6 o'clock is "FILTER"
    4 o'clock is "RINSE"

    Can someone help me fill in the gaps?

  6. Back To Top    #6

    Re: FNS Plus Poor Backwashing

    I'll give it a shot next season! What's the flow pattern when in rinse?

    Thanks

    Quote Originally Posted by Heckpools
    instead of going from backwash to filter, try backwashing, then to rinse and then back to backwash..( do this a few times) also, when you add the new de powder, add 1 pound LESS then it says too.. when you backwash not ALL of the de will come out, so if you continue to add the amount it says too, by the end of the season u'll have a caked up mess!

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    polyvue's Avatar
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    Re: FNS Plus Poor Backwashing

    Quote Originally Posted by Aurelius
    hello all -
    I think I have the same model for my pool.
    The system is about 9 years old.
    Over time, it has become difficult or impossible to read the labels on the controls.
    There are 6 settings that go around clockwise. The handle goes around and locks into notches at:
    12 o'clock
    2 o'clock
    4 o'clock
    6 o'clock
    8 o'clock
    10 o'clock
    I am sorry for the long post, I'm having some trouble explaining this.
    Basically what I need to know what these settings are for the filter system.
    Here are the settings that I do know:
    12 o'clock is "BACKWASH"
    6 o'clock is "FILTER"
    4 o'clock is "RINSE"

    Can someone help me fill in the gaps?
    Welcome to the forum, Aurelius...

    Though I can't answer your question, perhaps others here have experience with the Purex Triton filter and can.
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
    __
    View of spiral galaxy in Ursa Major NGC6217 - Hubble Telescope 2009

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    Join Date
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    Location
    New Jersey
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    Re: FNS Plus Poor Backwashing

    Aurelius: Missing notches would be Closed, Recirculate, and Waste. Should be easy to figure out. Waste will expel water direct to waste. Recirc will send it straight to the returns. Closed will not let it go anywhere. Pump will sound weird and pressure will ramp up fast. So just give the pump a bump until you know the one you are trying is NOT the Closed position. You don't want to leave the pump spinning in Closed position. I'd bump all three unknowns until I saw some water come out the waste pipe/hose. That's Waste. Then have someone put a hand over a return and bump the other two. The one that goes out the return is Recirc. The last one is therefore Closed. Of course, if someone is familiar with your unit and knows, that's even easier.

    Heckpools: Rinse is the same as filter except output goes to waste instead of back to the pool. It helps keep crud/DE out of the pool, but I don't see how it would clean any better than going B'wash/Filter. B'Wash/Rinse is the preferred approach for the reason I cited. One thing I do is watch the sight glass in the waste line (or on the MPV) and see how much new crud/DE is being exhausted with each mode change. I stop doing it when I no longer get a new shot of cloudiness when I switch to B'Wash.
    Current: 28,000G 18'x36' I/G AnthonySylvan Plaster; Waterway 60 sq.ft. DE Filter; 1.0hp x 1.65 SF Two-Speed (B2982) WhisperFlo; 2004-Present
    Previous: 40,000G 20'x40' I/G Koven unlined WWII salvage 5/8" marine steel; Lomart Stainless Sand Filter; 3/4hp Hayward SuperPump; 1946-2003 (managed by me from about 1964)
    Ancient Taylor K-2000, upgraded with Taylor CH, TA, and FAS-DPD, and TFT CYA tests.

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    Re: FNS Plus Poor Backwashing

    Thanks Durk!
    That will help me.

  10. Back To Top    #10

    Join Date
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    Location
    South Central NJ
    Posts
    3,192

    Re: FNS Plus Poor Backwashing

    The purpose of Rinse on both DE and Sand filters is to remove any debris that in the return side of the filter's plumbing during backwash.

    I have found adding a 30 filter cycle after Rinse and then repeating the backwash-rinse cycle to be somewhat more effective.

    Scott
    PoolGuyNJ
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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