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

Thread: Oversized Pump for 21' Above Ground pool

  1. Back To Top    #1

    Join Date
    May 2008
    Location
    IL
    Posts
    26

    Oversized Pump for 21' Above Ground pool

    When I backwash my pool, I usually get sand spitting out of the return for the first few seconds that I turn the pump back to filter mode. I've checked all the pipes in the filter and they all seem to be fine, no cracks or anything. So after doing some research, I think that I probably have a pump that is too strong for my pool. I don't know the HP of the pump off hand (I'm at work), but I know that when I bought the pump and filter combo, I accidentally told the pool guy that I needed it for a 27' foot pool instead of a 21' foot pool. Short of buying a new pump, is there anything I can do about this? Would getting smaller lines help anything or would that just make it pump shoot the water out that much harder? I'd rather not buy a new pump because of this, but cleaning up the sand everytime I backwash is becoming kind of a pain.
    21' Doughboy AGP
    1HP Pump
    Hayward Sand Filter
    Hawyard H-150 Heater
    Intex SWG

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879
    What size pump and what size filter do you have?

    Sand coming out of the filter almost always means that the filter is broken, often a cracked lateral.
    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

    Join Date
    May 2008
    Location
    IL
    Posts
    26
    I just opened the pool this morning and I checked all the laterals and there are no cracks. Sand just keeps dumping in the pool though every time the filter goes on or off. My pump size is 1HP (so I guess that isn't the problem). I can't find the gallons on the filter, but it is a big one. It says it pumps 25 Gal/min if that helps.

    Is it possible I have the wrong size sand in there? it says I should .45-.55 mm sand. Is that standard pool sand? I bought the sand at the pool store, but I don't remember seeing different sizes.
    21' Doughboy AGP
    1HP Pump
    Hayward Sand Filter
    Hawyard H-150 Heater
    Intex SWG

  4. Back To Top    #4
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879
    Pool filter sand is the same size world wide. I have heard of one pool store that carried the wrong size sand (too large), but that is quite unusual. Play sand from a yard and garden place will not work, but it won't get out of the filter either, since it is larger than filter sand.

    Other problems I have heard of are laterals that were lose in the main pipe, so sand could get through to the main pipe, and main pipes that were made of two pieces that slip fit together loosely enough that sand could get through there. Cracks in the laterals are sometimes difficult to spot and don't need to be very large to let sand through.
    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

  5. Back To Top    #5

    Join Date
    May 2008
    Location
    IL
    Posts
    26
    Thanks for the quick reply. I guess what I find strange is that from day 1 since I got this filter, I've had problem with sand getting into the pool. I've already replaced the laterals once and it made no difference. Maybe I just got a bad filter and it's time to replace it.
    21' Doughboy AGP
    1HP Pump
    Hayward Sand Filter
    Hawyard H-150 Heater
    Intex SWG

  6. Back To Top    #6

    Join Date
    May 2008
    Location
    IL
    Posts
    26
    Sorry to keep bringing this up, but I'm really trying to get to the bottom of this and I just thought of something else.

    One thing I found strange about this particular filter is that the center pipe is not long enough to allow the lateral house to sit all the way to the bottom of the filter. Basically, there is a few inches of sand, then the laterals start. Could this be the problem? Should the pipe be long enough so that the lateral house (sorry if I'm calling it something it isn't) sits on the very bottom of the filter? I'm thinking maybe once it gets under pressure, the whole unit is sliding up and down causing sand to get in. Any thoughts?

    I figure I can maybe replace the pipe with a custom fit PVC pipe if you think that might help.
    21' Doughboy AGP
    1HP Pump
    Hayward Sand Filter
    Hawyard H-150 Heater
    Intex SWG

Posting Permissions

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