Return Pump...

Discussion in 'General Discussions and Advice' started by Express Reef, 23 Dec 2011.

  1. Express Reef

    Express Reef

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    Hi All,

    Just want to know, how do you work out the size of the return pump to the volume of the tank? How big return pump do one need for 480L...

    Thanx
     
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  3. RiaanP

    RiaanP Moderator

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    Do you run a DSB?

    How wide is your sump, front to back?

    in my experience you need a pump that will give you a water head of between 6 and 10mm over the last divider in your sump. That is if you are running with a DSB
     
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  4. Express Reef

    Express Reef Thread Starter

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    Sump 900 x 600 x 600 with DSB, my current pump is rated 2700L per hour but dont know if it is too little... think of getting a stronger flow...
     
  5. RiaanP

    RiaanP Moderator

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    jip, too small

    according to my calculations, to get 10mm head over the divider on 600mm wide sump, you would nee a pump that delivers 3961L/h at your return line maximum point. So look at that graph on the pump box. Measure your display rim height from the floor.

    I reckon at least a 5000 or more size pump. Or maybe another similar pump as the one you got.
     
  6. rakabos

    rakabos

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    You can have as much flow as you want, within reason. The limiting factor will be the width of your pipes and if it can support the waterflow coming through it.

    I would say at least 4000. I am running 4500lph on my 700L and its perfectly fine
     
  7. RiaanP

    RiaanP Moderator

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    this, depends entirely on the sump width.

    1.5 times turnover on a sump that is 300mm wide will give a completely different flow rate than a sump that is 600mm wide.

    This old rule, is most likely the cause of a lot of the guys with bigger tanks and sumps, getting detritus settlement on top of the DSB. Then proclaim that DSB in general do not work.

    If I do have this formula correct
    Q = 1.84(L – 0.2H)H3/2

    Then for a head height of 10mm over the divider, you need for different sump width:
    300 - 2000L/h
    450 - 3000L/h
    600 - 4000L/h


    That is water delivered at the top of your return line.
    That formula gives you the cubic litre per second flow rate.
     
    Last edited: 23 Dec 2011
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