overflow problems

Discussion in 'Beginner Discussions' started by Cois, 21 May 2016.

  1. Cois

    Cois

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    Hey guys

    I need help I build myself an overflow today with 20mm pipe but the flow out of this thing is very very slow .... what could be te problem ....
     
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  3. Richard01

    Richard01

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    Post a picture, what size return pump do you have?
     
    Last edited by a moderator: 20 Jul 2016
  4. Christo

    Christo

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    20mm is quite Small!! I Personally won't go smaller than 32mm! I Normally use 50mm!

    Like @Richard01 said, Tell us a bit more about your System. And some PIC's Might help.
     
    Last edited by a moderator: 20 Jul 2016
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  5. Cois

    Cois Thread Starter

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    Hey guys

    okey I just build and test it outsod in a drum but the flow is terrible out of it
     
  6. Cois

    Cois Thread Starter

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    50 mm for an 3 foot tank is quite big but ill try it ...... next question how far apart do I place the dividers in my sump its a 40 litre tank 60 cm across ....
     
  7. Cois

    Cois Thread Starter

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    20160521_192638.jpg
     
  8. Cois

    Cois Thread Starter

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    I couldnt find any other t piece
     
  9. Christo

    Christo

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    On a 3foot tank you can get away with 36mm/32mm can remember the exact size! All depends on what size Return pump you running!
     
    Last edited by a moderator: 20 Jul 2016
  10. Christo

    Christo

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    Last edited by a moderator: 20 Jul 2016
  11. Cois

    Cois Thread Starter

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    I got an 1000lph return yeah was off cuts condute here at my house ... why ??
     
  12. Jacojs

    Jacojs

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    Hi @Cois

    Are those screws on the T-Piece?
     
  13. RiaanP

    RiaanP Moderator

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    That will work, as long as the T-piece will not leak or pull in air. The screws will not be under water and will only pick up surface rust like any other metal object around the tank.

    Conduit will work as well, but as you experienced, the flow rate will be terribly slow. What can help is if you increase the first section to be thicker.
     
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  14. Cois

    Cois Thread Starter

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    okey yes thats screws but I plastic weld the lid so its one box no aitlr can get in there but what would you guys sugest to just get 50 mm and start over ???
     
  15. RiaanP

    RiaanP Moderator

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    yes

    But even better. Get the tank drilled and fit a proper overflow.

    Years ago I also played around with one of these overflows. Believe me, they are prone to failure. Small air bubbles can and do travel all the way down the first segment, collecting in the "bridge" section where it goes over. The height of the T piece outside plus water flow rate determine the water level inside the first segment. Too low and bubbles do collect a lot easier. Too high and the flow rate is slower. Your setup, I think the T piece is too low.

    Anyway, as the bubbles collect, they eventually lead to siphon break. Can drill a 6mm hole into the bride highest part and fit an airline hose to it. That would help you to suck out the air to start the flow. The other end of the airline can then be connected to the old style powerheads that have a venturi attachment. Then it will continuously suck out air bubbles and would help to prevent siphon breaks. You still need to maintain the overflow weekly to ensure that it does not have air inside. The airline should not have light from your light fixture shining on it. Else algae grows inside, that could lead to blockage. Black micro irrigation line works better.
     
    Last edited: 22 May 2016
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