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Thread: DE - After backwashing...

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    DE - After backwashing...

    Is it necessary to add more DE after backwashing? If so, how does one know how much to add?

    Thanks in advance.
    25,000 gallon in-ground pool, Nautilus DE filter

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    Mod Squad woodyp's Avatar
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    Re: DE - After backwashing...

    Are we talking about a DE filter or a sand filter here?
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    Richard320's Avatar
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    Re: DE - After backwashing...

    Quote Originally Posted by want2betroublefree
    Is it necessary to add more DE after backwashing? If so, how does one know how much to add?

    Thanks in advance.
    Yes. it is necessary. The DE is actually what does the filtering. The screens are just what holds it.

    How much depends on the filter. There should be a label on it somewhere that tells the make and model, we can help if you can get us that. Otherwise, it will be a guessing game where you post pictures and measure things and we try to figure out what you have.
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    Re: DE - After backwashing...

    It's a Nautilus NS 36 (reading notes of previous owner).

    Thanks for the help.
    25,000 gallon in-ground pool, Nautilus DE filter

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    Re: DE - After backwashing...

    Here is the manual for it

    http://www.pentairpool.com/pdfs/NautilusNSOM.pdf

    It shows a full capacity brand new is 3.6 pounds. From reading after backwashing you should add roughly 80% of DE after backwashing.

    So you should add roughly 2.88 pounds or 45 ounces by weight.
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    Re: DE - After backwashing...

    Does length of time backwashing affect how much to add again?

    I'm wondering if I haven't been putting enough in because there seems to be a yellow-brownish growth on the floor in the deeper end of the pool.
    25,000 gallon in-ground pool, Nautilus DE filter

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    Re: DE - After backwashing...

    From my experience and reading, backwashing will only get out about 80% no matter how long you backwash. Eventually when you are backwashing the water will come out clear and will not get anymore DE out.

    If you have yellow-brownish growth on the floor that could be a whole other issue.

    What I would do is start a new post with the statement below

    "there seems to be a yellow-brownish growth on the floor in the deeper end of the pool."

    Post a full set of test results and we will be able help you. I said make a new post so all relevant information to this post stays here and then you can get help with testing and such in the new post.
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    techguy's Avatar
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    Re: DE - After backwashing...

    Photos can also help us to understand your issue.
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