Return Pump Placement

Discussion in 'Sump' started by Wickette, Feb 18, 2019.

  1. WicketteValued MemberMember

    Ive got 15g sump tank nearly complete (some gluing and fishing touches left),

    One thin Ive been noticing is just about every source has the return pump at the bottom of the sump, why is that? I assumed it makes more sense to put it a few inches bellow the water level incase the intake pipes get blocked up, then only 1-2 gallons gets pumped into the main tank, if the pump is at the bottom and the intake is blocked all the water in the sump tank is pumped into the main tanking causing it to over flow
  2. ryanrModeratorModerator Member

    Some sump setups have the return pump sitting on egg-crate or similar to raise it from the sump floor.

    Generally it (the pump) is placed further down owing to the evaporation.

    When water evaporates, the level drops in the return section, as this is the only section of the setup that doesn't have a 'self-levelling' aspect to it. So to avoid running the pump dry in high evaporation situations, the pump is further down.
  3. WicketteValued MemberMember

    Im using a slotted basket, would be the same effect as egg crate.
    as long as evaporation is accounted for, there's no reason to place the pump low, right? I cant think of any benifits of placing the pump on the bottom aside from evaporation.

    Aside from less water overfilling the tank in case of a blockage, having the pump elevated leaves room for more media before the water is returned. on a 750gal pump like mine, placing the pump on the sump tank floor gets me a return flow of 380gph, lifting it 6 inches gets 410gh flow. And any waste that makes it past the filters would be sitting on the tank floor elevating the pump means less crud getting into the impeller.

    Thats a lot of pros with 1 very avoidable con AFAIK
  4. ryanrModeratorModerator Member

    Yep, you're correct, there's a lot of pros to running your pump that way.

    I never really worried about it when setting up my system. (My tank and sump were completely custom) I mean, I considered it (the possibility of clogged drain pipe), and with the size. During my research, I read a lot about sump to display setup, so I considered my options.

    I alleviated my risks by using PVC piping that was unlikely to get blocked completely, and a partial blocking would still allow a flow rate greater than the return pump, that was step 1. Step 2 was a little more mathematical, but I allowed for the extra volume that could possibly go back into the tank, and my overflow weir height was lower than the top of the tank. Enough to be able to handle the extra volume should the whole return section be drained and sent to the tank.

    My setup as follows, the brown line represents the hood when closed, the dotted line is the top of the tank glass, so even with the extra space I allowed, with the hood closed, it always looked "full"

    There might be some images here on FL of the setup with hood up, and hood down.... I'll see if I can find them.
  5. WicketteValued MemberMember

    Thanks, not losing something critical as my only concern with elevating the pump.

    My tank's not drilled, so Im using a heavily modified version of the King of DIY PVC pipe overflow "box" , using two 3/4" pvc intakes that hook upto a 1.5" pipe, and my weir is a $5 Marina medium breeder box with slits sawed in. there is a very small but real chance of a siphon break which would have the same effect of a blocked intake.

    being diy, the sump tank chambers dont have a water tight seal, so it would take a while but all the water would eventually reach the pump if it was on the bottom.