Discussion in 'Beginner Discussions' started by Brian83, 13 Sep 2012.

  1. Brian83


    7 Sep 2012
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    I have a question about sumps and in particular the retun line.

    1. Does the return line have to be the same thickness as the drainage line? I can't see how one would have a pump with a 40mm nozzle, because you would surely be talking about a turn-over of 7000+ litres per hour. I can imagine how having a 40mm hole for your drainage line would allow for water to flow freely, for pretty much any tank size we can realistically keep in an average household, to be beneficial.
    2. When the power goes out the water in the return line would fall back into the sump. This, I can imagine, would create a siphon. Will a non-return valve above the return pump stop the siphon or would it be better to drill a small hole below the surface of the water in your DT to eventually break any siphon that may be created during a power outage?
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  3. Jayceew


    20 May 2011
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    Pretoria East
    Hi Brian

    Your return pipe from the return pump is smaller than the overflow pipe. Dependent on the pump it can be around 10mm to 20mm(average) but your overflow(drainage) would be around 50mm which is the most common size used.

    To prevent the back siphon a small hole works well but these tend to block so watch out for that. Perhaps you can design the tank so that your return line from the pump does not sit too low below the water level, so even if there is back siphon it will not be enough water volume to flood the sump.
    Last edited: 14 Sep 2012
  4. madmike


    10 Aug 2011
    Likes Received:
    Hi could someone please help me.
    Iv built a small sump for my nano its a 3 stage sump.
    First stage is filter mat,then ceramic noodles, then live rock. Not sure if i should put live rock or bio balls?
    In the second stage i want to put my scrubber,heater and not sure what else?
    Should i just put those items or can i put something else to better it?
    Third stage is just the return pump.
    The sump isnt very big its 350Lx268Wx240H thats all water.
    Last edited: 11 Dec 2012

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