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Thread: Using DE with a sand filter

  1. Back To Top    #1

    Join Date
    Jul 2010
    Pardes Hanna, Israel

    Using DE with a sand filter

    Hi All,
    Wasn't sure where to post this....

    Basically everything is running smoothly with my pool, and the water is "fine".
    The only problem I am trying to control now is cloudiness that is the result of chalking (paint dust coming off into the water).
    I am keeping things under control by running the pump about twice as long as I would if it weren't for the chalking, but the water is never even close to sparkling clear.

    I was thinking about adding DE to my sand filter as is suggested in pool school and a few threads on the forum.
    My problem is that my waste line is not connected to the sewage system. When backwashing, the water simply floods a section of our backyard and waters the trees.

    I read a bit and realized that DE is hazardous and I should not just backwash it onto the ground.
    Is this correct? If so, any thoughts on how I can "grab" the DE when I backwash?

    Oh, and of course - if I do manage it, what is the proper way for disposing of DE?
    15 KL (3300 imperial / 4000 US gallons) IG fiberglass pool, 61cm (24") Lacron sand filter, 3/4 HP Hayward pump

  2. Back To Top    #2

    Join Date
    Jun 2011
    Cape Girardeau, Mo

    Re: Using DE with a sand filter

    I use it occasionally and backwash it to the ground. From my understanding it is only harmful if you breath the dust and that is why it is classified as hazardous but it is not in itself poisonous or anything,

    It can also be used to control ants when sprinkled around the outside of a house it is like little razor blade to ants and other bugs but is harmless to mammal's.
    Steve Frakes
    15' X 48'' Intex Metal Frame
    Intex Sand Filter 16'' 2650 GPH
    Taylor K-2006 Test Kit
    BBB and Borated

  3. Back To Top    #3
    stev32k's Avatar
    Join Date
    Mar 2009
    Mobile, Alabama

    Re: Using DE with a sand filter

    I've been adding two or three cups of DE in my sand filter after almost every backwash for about two years. The backwash goes on the ground just outside the pool area and I have not seen any sign of the DE. I expected to see a buildup in the backwash area over time, but so far I can't see any.
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

  4. Back To Top    #4

    Join Date
    Jul 2010
    Pardes Hanna, Israel

    Re: Using DE with a sand filter

    Thanks guys.

    I've done some more reading on the subject. I am definitely not going to use DE unless I have a way of removing it safely.
    I still have no clue as to how I can do this, but I would like to share what I have read about DE, and ask that you be careful when using it.

    Apparently there are two kinds of DE:

    1. DE as it is found in nature - mainly composed of Amorphous silica. It dehydrates on contact which is why it is an effective insecticide. It does not pose a significant health hazard to humans (unless you decide to inhale it directly...)

    2. DE for filtering - mainly composed of crystalline silica. Is the result of treating natural DE with heat causing the silica to assume its crystalline form, hence its sharp edges.
    This form is what we buy as filter media, and is the kind which is hazardous to health (if dust is inhaled. small amounts over long periods are also a problem since particles lodged in the lungs cannot be removed, making the effect cumulative)
    The related disease is called silicosis. It is an irreversible lung condition which can be fatal.

    I believe there is a potential hazard simply due to the possibility that people may not be aware of the difference as they are both sold as DE (with filtering media DE being the more common type)

    An excerpt from Wikipedia:

    "The type of hazard posed by inhalation depends on the form of the silica. Crystalline silica poses a serious inhalation hazard because it can cause silicosis. Amorphous silica can cause dusty lungs, but does not carry the same degree of risk as crystalline silica. Natural or dried diatomite generally contains very low percentages of crystalline silica. Diatomite produced for pool filters is treated with high heat (calcining) and a fluxing agent (soda ash), causing the formerly amorphous silicon dioxide to assume its crystalline form."

    Keep safe.
    15 KL (3300 imperial / 4000 US gallons) IG fiberglass pool, 61cm (24") Lacron sand filter, 3/4 HP Hayward pump

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