Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 6 of 6

Thread: Backwashing questions

  1. Back To Top    #1
    Martha_D's Avatar
    Join Date
    May 2012
    Location
    Putnam, NY
    Posts
    67

    Backwashing questions

    When do I need to backwash? I read somewhere something about the pressure... the pressure on my filter is around 20 right now.

    also... should the main drain valve be open while backwashing or the skimmer valve or both?

    thanks
    34K gallon, Hayward S240 sand filter, in ground, gunite... not sure of pump size and flow rate

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Backwashing questions

    You backwash when the filter pressure goes up by 25% over the starting pressure. If you don't know your clean filter pressure, you might as well backwash now so you can find out what it is.

    You can leave the skimmer/drain valve(s) alone when backwashing.
    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
    Martha_D's Avatar
    Join Date
    May 2012
    Location
    Putnam, NY
    Posts
    67

    Re: Backwashing questions

    Thank you Jason, this brings up another question. I have been running the pump with skimmer open and main closed. Is this correct? Im not really sure what the main drain is used for...
    34K gallon, Hayward S240 sand filter, in ground, gunite... not sure of pump size and flow rate

  4. Back To Top    #4
    WestSidePool's Avatar
    Join Date
    Jun 2009
    Location
    Cincinnati, OH
    Posts
    424

    Re: Backwashing questions



    Like Jason said, when you get your starting pressure (right after you add your filter media), you set your green dial to match the black pressure line. When the dial reaches red you know it's time to backwash.
    Eric

    IG 17x33 Grecian - Vinyl Liner (21k gallons), Hayward Pro-Grid DE 4820 filter, Hayward Super Pump, CompuPool SWG CPSC36, TF-100 Test Kit

  5. Back To Top    #5
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Backwashing questions

    Typically you want the skimmer all the way open and the main drain partially open. You want the main drain at least partially open so the pump can still draw water even if the skimmer gets clogged and also so that the deep water near the drain gets circulated well. Having both on also improves the overall efficiency of the system.

    Some pools work well with the main drain all the way open, others require it to only be partially open so that the skimmer will still skim effectively. If in doubt, go for partially open.
    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

  6. Back To Top    #6
    Martha_D's Avatar
    Join Date
    May 2012
    Location
    Putnam, NY
    Posts
    67

    Re: Backwashing questions

    ok, thanks guys!
    34K gallon, Hayward S240 sand filter, in ground, gunite... not sure of pump size and flow rate

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •