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Thread: Amount of DE to use after backwash

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    jgofnj's Avatar
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    May 2013
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    Amount of DE to use after backwash

    Hi all, been using this method for the second year and am doing great and saving a ton of money, what an awesome site this is and what a great method TFP method is.

    So my question has nothing to do with the chemical levels but the amount of DE to replace when back-washing my DE filter. I have been told to use 6 lbs. of DE for the size of my DE filter. Since my pool is kept very clean, I only back-wash the filter once a season (when the pressure builds up) and replace it with 6 lbs of DE. I notice this time and the last time I did this that there was a lot of gray-ish power at the bottom of the pool. When I asked someone about this, he told me that the 6 lbs. is for when the filter is completely cleaned and there is no DE in it at all, but that when I back-wash it, no mater how good I do it, I really only need half (or 3 lbs.) of DE. Is that correct? That would explain that what I am seeing at the bottom of the pool after adding 6 lbs. of DE after just doing a back-wash is DE accumulation. FYI - When I close the pool, I take apart my DE filter and clean each filter until there is no DE at all left so adding 6 lbs. after doing that is not an issue.

    Thoughts?
    20,000 gal, In-Ground (built in 2007)
    Vinyl lining / 1HP Hayward SuperPump / Hayward Pro-Grid DE Filter / Hayward Gas Heater / Liquid Chlorine,Bleach (4 Gallon Liquidator)
    Dohney Discovery Robot
    Testing Method: TFTestkits/TF-100

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    Re: Amount of DE to use after backwash

    The amount of DE to put in depends on what type if filter you have and what the manufacturer reccomends. If you still have your owners manual from the filter take a look and it will tell you. You should be backwashing more than once a season. Your filter would not be filtering at capacity that way. If you put your hand over the return jets and the water is coming out very weak, it's time to backwash. I know people who do it once a week no mater what. I do not. I do it when the return slows down.
    36,000 gal IG vinyl. Haywood pump and heater Hayward DE filter blue diamond robot. Hayward Aqua Rite SWG AQR-15

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    JasonLion's Avatar
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    Re: Amount of DE to use after backwash

    Our rule of thumb is to use 80% as much DE after backwashing as you would use when the filter is opened up and cleaned out.

    Adding too much DE should never result in DE getting into the pool. If there is DE in the pool something is wrong. If DE is constantly getting into the pool the problem is likely to be in the filter. If DE only gets into the pool right after you add DE to the filter then the problem is more likely to be with the main valve (often a bad spider gasket).
    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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    jgofnj's Avatar
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    May 2013
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    Re: Amount of DE to use after backwash

    Thank you guys. I just found a previous post detailing the process and as you just said Jason, it says to use 80% when back-washing. Thanks again.

    As for DE getting into the pool, I will investigate that further.
    20,000 gal, In-Ground (built in 2007)
    Vinyl lining / 1HP Hayward SuperPump / Hayward Pro-Grid DE Filter / Hayward Gas Heater / Liquid Chlorine,Bleach (4 Gallon Liquidator)
    Dohney Discovery Robot
    Testing Method: TFTestkits/TF-100

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