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Thread: More returns or more intake suction lines

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    Water_man's Avatar
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    More returns or more intake suction lines

    The pool I inherited from a previous owner had originally two ¾” returns, one main drain, a skimmer and a 11/2" Polaris line. After awhile the previous owner shut off the main drain because water from the water table leaked into it. When I inherited the pool the Polaris line had no use because the auxiliary pump didn’t work and I got myself a robot instead.

    Although I am in charge of the pool chemistry, I need the pool guys for the plumbing. At one time a pool guy suggested to turn the Polaris line into a return line, and I thought it was a good idea. I got three returns instead of two. Now comes another pool guy (with twenty years experience) and he suggests to turn this return line into a suction inlet line, to compensate for the loss of suction rendered by the closing of the main drain. He’s saying that suction is more important than returns.
    Any thought about this statement?
    This is my ticket for Heaven (when all's working..) :
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    Mod Squad Bama Rambler's Avatar
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    Re: More returns or more intake suction lines

    Are the return lines 3/4" or just the eyeballs with larger lines to them?
    If the lines themselves are 3/4" I'd definitely convert the other line to a return.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Water_man's Avatar
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    Re: More returns or more intake suction lines

    The return lines are 3/4" and they end up flush with the wall. At the time when the pool was built they didn't install eyeballs yet.
    I went ahead with a DIY gadget and installed removable eyeballs for better circulation.
    But keeping in mind that the original design featured a main drain and a skimmer with two returns, doesn't it make sense to restore the original intake flow of the pump?
    This is my ticket for Heaven (when all's working..) :
    22k Gal gunite IGP, 38 SF Anthony DE filter, 1 HP Hayward Super Pump
    380k BTU Raypak Natural Gas Heater (Model RP405A) and solar cover
    8 gal Liquidator w/ 12% bleach, Dolphin Diagnostic Advantage robotic cleaner. 3800 ppm salt, 50 ppm borates.

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    Mod Squad Bama Rambler's Avatar
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    Re: More returns or more intake suction lines

    Think about it this way. It takes four ¾" lines to equal one 1½" line. So right now you're only able to pump out about half the volume you can draw in. Adding the MD back isn't going to help that situation but if you convert the cleaner line you'll be able to pump more even with just the one skimmer.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Water_man's Avatar
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    Re: More returns or more intake suction lines

    It makes sense perfectly. Flow rate is linearly dependent on the cross section area which is linearly dependent on the square of the diameter. The skimmer's intake is an 11/2" pipe. Obviously two 3/4" on the return side aren't enough. You nailed it, my friend.
    This is my ticket for Heaven (when all's working..) :
    22k Gal gunite IGP, 38 SF Anthony DE filter, 1 HP Hayward Super Pump
    380k BTU Raypak Natural Gas Heater (Model RP405A) and solar cover
    8 gal Liquidator w/ 12% bleach, Dolphin Diagnostic Advantage robotic cleaner. 3800 ppm salt, 50 ppm borates.

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