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Thread: To backwash or not to backwash -- that is the question!

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    To backwash or not to backwash -- that is the question!

    Is it true that your filter (I have a sand filter) works better when it's dirty? And that you shouldn't backwash until the pressure gauge reads 10 higher than normal? I've been backwashing whenever the pressure gauge goes 5 higher than normal, but maybe I should wait. (Lots of rain here, so water level isn't a problem.) Also, if I don't backwash at least once when vacuuming, I seem to have worse suction. I always thought that was because the filter was clogged, but maybe there's another reason?

    Thanks for your help ...
    -----------------------------------
    26000 gal, in-ground, vinyl pool
    Hayward S200 sand filter, 1 skimmer, 2 returns
    BBB since the first month! :-)

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    Mod Squad JohnT's Avatar
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    It can filter finer particles when slightly dirty. If the flow drops, your circulation won't be as good, but it will clean the water it does filter.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    In the Industry

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    Re: To backwash or not to backwash -- that is the question!

    Quote Originally Posted by singerteacher
    Is it true that your filter (I have a sand filter) works better when it's dirty? And that you shouldn't backwash until the pressure gauge reads 10 higher than normal? I've been backwashing whenever the pressure gauge goes 5 higher than normal, but maybe I should wait. (Lots of rain here, so water level isn't a problem.) Also, if I don't backwash at least once when vacuuming, I seem to have worse suction. I always thought that was because the filter was clogged, but maybe there's another reason?

    Thanks for your help ...
    A slightly dirty filter works better than a perfectly clean one. The 10 psi rule for backwashing is a rule of thumb. For your pool, it might be 5, 8, or 12. Experiment a bit; try going to a 10-psi increase before backwashing and see how your water looks. Note the pressure at the returns. Just after backwashing, your pressure at the returns should be good. When the flow from the returns becomes weak, that is a sign that your filter needs cleaning.

    You might want to try vacuuming to waste. . . then what you vacuum won't go thru the filter and you won't have to backwash it. Just a thought.
    ~Jules~

    My pool: INDOOR 13x27 rectangular fiberglass, built ~2001, BBB, TA-60 sand filter, Hayward two speed pump (1 hp/0.33 hp), 3/4 hp booster pump for solar heater
    Taylor K-2006 test

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    My clean filter pressure is 7 lbs and I backwash when it hit 25 lbs. I have to backwash usually once when vacuuming to keep the vacuum strong. The first vacuum of the season is always to waste.
    Hotrod30

    20 X 40 foot vinyl Borates and Salt Pool
    Rolachem Chlorine Feeder
    Hayward 27 inch sand filter with 80 lbs of pea gravel
    Jacuzzi Splash Pak SP55 DE filter in parallel
    Pentair VF3050 pump

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    Thank you!

    As usual, a bunch of great replies. Thanks!
    -----------------------------------
    26000 gal, in-ground, vinyl pool
    Hayward S200 sand filter, 1 skimmer, 2 returns
    BBB since the first month! :-)

  6. Back To Top    #6
    Don't you lose a ton of water when you vaccum to waste? I do'nt see the value in that but I'm just a newbie so I don't know much. I just backwashed my D.E. filter last night and it was amazing how much pressure I was getting at my returns. I didn't realize how bad I needed to backwash.

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    JasonLion's Avatar
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    Vacuuming to waste is worth it if you are vacuuming up some serious muck that would clog the filter quickly or cause chemical problems.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Quote Originally Posted by neckbeardus
    Don't you lose a ton of water when you vaccum to waste? I do'nt see the value in that but I'm just a newbie so I don't know much. I just backwashed my D.E. filter last night and it was amazing how much pressure I was getting at my returns. I didn't realize how bad I needed to backwash.

    After the cover comes off (Link-Loc), the pool is completly full from snow and spring rains. I start the pump and add a large amount of shock to the water in the evening, let the pump run for a couple of hours in recirc and then shut the pump off. Next morning I vacuum to waste; even thou I can't see the bottom; until the water level comes down to about were it should be. Even thou you can't see the bottom, you know where the main dirt piles and junk will lay. Also, I am only using the sand filter.
    Hotrod30

    20 X 40 foot vinyl Borates and Salt Pool
    Rolachem Chlorine Feeder
    Hayward 27 inch sand filter with 80 lbs of pea gravel
    Jacuzzi Splash Pak SP55 DE filter in parallel
    Pentair VF3050 pump

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