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Thread: new cartridge filter not filtering

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    new cartridge filter not filtering

    I just installed a Pentair Clean and Clear 420 filter and it does not seem to be filtering, the water remains cloudy. I opened up the filter and made sure everything was sitting properly. I must admit that the pool is very cloudy since I wasn't able to clean it while I was installing all new pool equipment. So I had a lot of algae and dirt which I took care of by shocking the pool and using Algaeside. So now I have a bunch of dead algae that does not get trapped by the new filter.

    A PB told me that I can add some DE to the filter to help it, does this sound correct, if so how much.

    I bought this filter because I did not want to deal with DE, my old filter was a DE filter.

    25K Pool Kidney Shape
    Water Slide
    320Sqft Pentair Clean and Clear Cart Filter
    1.5hp Pentair WhisperFlo pump
    400k BTU Hayward LoNox Heater

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD
    A cartridge filter can take a couple of days to clear up cloudy water. DE filters are often much faster than that. You may have simply not given it enough time. You should see some visible improvement each day, but it won't be clear for a couple of days.

    Less likely possibilities include an improperly seated cartridge allowing water to go through without going through the cartridge, if you have a multi-port valve it might not be in filter mode, cloudiness from sources other than algae that are too fine to filter out, or maybe the algae isn't all dead.

    I wouldn't normally add DE to a cartridge filter. The only case in which adding DE could possibly help is if the cloudiness is from very fine particles that get through the cartridge and that doesn't seem like the most probable cause. Plus adding DE can shorten the life of the cartridge.
    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

  3. Back To Top    #3
    I know in the clean an clear series (not sure about the multi cart clean and clear plus series) Pentair recommends adding DE to the filter ON FIRST STARTUP ONLY. Check the manual and see what it says.

  4. Back To Top    #4
    when i opened my pool it was very cloudy, but not full of the green stuff. but even with pool clearer and the filter running 24/7 it still took about 4 days for it to clear, but that was with a sand filter, but i read that a cart filter, filtered the same amount as a sand filter. so i would guess it would be the same, but i also had a lot more water to filter. FWIW

  5. Back To Top    #5
    I just checked the owners manual a little more carefully. On startup you should add .75Lb DE for every 100sqft. Hopefully this will help
    25K Pool Kidney Shape
    Water Slide
    320Sqft Pentair Clean and Clear Cart Filter
    1.5hp Pentair WhisperFlo pump
    400k BTU Hayward LoNox Heater

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