How to choose the correct return pump

Discussion in 'Pumps and Waterflow' started by MerlinT, 24 May 2016.

  1. MerlinT

    MerlinT

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    Hi Guys
    My display tank is 360lt and my sump is 90lt. How do I choose the correct return pump and which will I need for my application. My over pipe is 50mm and my return pipe is 20mm. My display pumps are 2 x WP25 Jebao wave makers.
    I am currently using a Boyu FP-58 return pump rated 2500lt. Although it is doing the job, I really want to get more water flow through my sump.
    Thanks in advance
    M
     
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  3. Quentink

    Quentink

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    Tagging
     
  4. RiaanP

    RiaanP Moderator

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    Do you have a DSB? Or what is in your sump for filtration?
     
  5. MerlinT

    MerlinT Thread Starter

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    No DSB, just some liverock and skimmer
     
  6. Quentink

    Quentink

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    Hi @RiaanP, Does it make a difference if you have a DSB?
     
  7. MerlinT

    MerlinT Thread Starter

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    Probably does as you need a lot of flow in order for detritus not to settle on your DSB. I could be wrong with this comment but let's hear what the more experienced guys have to say.
     
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  8. r0ckf1re

    r0ckf1re

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    Wont your return also make a difference?

    Your pump can be strong an pump the water back into your DT quick, but the water has to also come back to your SUMP quick enough to supply that return pump so you don't end up running it dry.
     
  9. Christo

    Christo

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    In That case I would increase the flow!! I Personally Love a "BIG" Return Volume!
     
    Last edited by a moderator: 20 Jul 2016
  10. mariusmeyer

    mariusmeyer

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    With a single 20mm return line you wont be able to push huge amounts of water through it does not matter how big a pump you connect to it. The back pressure in the pipe will be too much. I think you will be lucky to get 3000lph through it after taking headloss into account. The single 50mm overflow will handle the flow back to the sump easily. Just bumping your return line up to a 25mm will give you a lot more throughput. With your tank volume i would say that 2000lph should be enough flow through the filtration. Some people actually prefer a slower flow through the sump. Some people also try and match the return pump volume with the amount of water that the skimmer pump can do.
     
  11. RiaanP

    RiaanP Moderator

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    yip, with DSB you do not want excess settlement on the sand. Nice strong flow helps a lot. Filter socks and in line skimmer helps as well to limit settlement. Although flow should not be too strong to cause sandstorms. And a waterfall effect into DSB chamber is not a good idea. That is why I like the dividers on both ends to have a 10mm or less difference in height. And I prefer the flow to be strong enough so that you end up with between 6 and 10mm head height over last divider. And here the width of the sump plays a major role. As every 150mm in width needs an extra 1000L/h pump delivery into the display.

    Take note, a 2000L/h pump does not deliver 2000L/h. Not after head height loss and friction plus pressure, plus 90 degree elbows and all other factors comes into play.

    Lastly, the length of the overflow in the display should be able to handle the flow rate as well. Too small an overflow and you end up with a rather high water head in the display, leading to fish and snails easily flushing over into the overflow. Longer / wider overflows, preferably double the length than your sump is wide (front to back) will help a lot in having a low water head.

    Water head is the difference between the actual water surface and the top of the overflow. The water that would drain to your sump when return pump switches off (providing you got a good siphon break)
     
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