Help or Advice

Discussion in 'General Discussions and Advice' started by THE ANIMAL, 13 Jun 2009.

  1. THE ANIMAL

    THE ANIMAL

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    :please: CAN ANY ONE HELP.
    I'f put in a close loop system in my display tank white an poolpump on. Everything is working well only it is pumping my tank full off airbubbles. Everything is sealed. Can anyone tell me why and how to fix it.
     
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  3. jacquesb

    jacquesb Retired Moderator

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    Hi Animal - I also had a pond pump on a "closed loop" type "thing"/system a while back (I only used 50mm piping, which "hung" over the top of my tank, with both the "inlet" as well as "outlets" in the tank/water.....

    I too have the same issue - with air-bubbles...... This definitely came from air seeping into the piping SOMEWHERE..... I never found the problem, because the pump "broke"...

    MY pond pump was a 26000 litre per hour pump - NEARLY as strong as a swimming pool pump....
    ;)

    I am also "tagging along" on this once..... because I would still like know how/what......

    As I said - I MUST be because of air coming in somehow..... Usually, you MUST have a complete vacuum in the piping, otherwise you WILL always have these air bubbles being blown into your tank.

    :(
     
  4. THE ANIMAL

    THE ANIMAL Thread Starter

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    Ok Jacques lets houp there are someone out there that can help us. But it is not geting air in on the piping because I pvc weld it and then sealed it with silicon. Can anay one give us some advice.
     
  5. Mekaeel

    Mekaeel Moderator MASA Contributor

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    I can only think of the same thing, air is being sucked it from somewhere. Is it possible to submerge the pump into your sump and see if the problem stops. This way, in case there is air being sucked in somewhere from the pump, it will suck from the water in the sump.
     
  6. jacquesb

    jacquesb Retired Moderator

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    Sorry Mekaeel - unfortunately, you cannot submerge a swimming pool pump. They are NOT submersible pumps.........
     
  7. Manic

    Manic Moderator

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    Hey Guys,

    It's getting air in the system from something called cavitation. Its because of the high speed that a pool pumps turbine spins at. It causes the pressure to decrease at some points along the turbine so much that water will actually boil at a lower temp. This causes bubbles to form. The only option it to turn down the speed of the motor which isn't possible with that ac motor.

    Could be wrong, but im pretty sure.
     
  8. THE ANIMAL

    THE ANIMAL Thread Starter

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    Mekaeel no it is not possible to submerge the pump, but to eliminate that I also got 3 pumps that I tested same thing. Can it be that the pump are to powerfull? 30 000 lph.
     
  9. THE ANIMAL

    THE ANIMAL Thread Starter

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    Yes I spoke to Hennie (Reef Manic) today and he also spoke aboat the cavitation. So in short this pump will not work?
     
  10. jacquesb

    jacquesb Retired Moderator

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    Hi Animal - just a quick question - what brand is the pump? I have a Speck in the garage - 0.4kw - I am wondering how I could possibly use this pump......
     
  11. Manic

    Manic Moderator

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    Not unless you limit the flow at some point after the pump, this should cause a pressure increase and in theory will stop the cavitation. So maybe just add a ball valve after the pump and then close it untill the bubbles stop. This will allow you to use the pump but it will have less flow, and there will be pressure in the pipes which could be a problem.
     
  12. jacquesb

    jacquesb Retired Moderator

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    HHHmmm - just had a "brain wave" (funny thing for me to have over a weekend) ;)

    Would it work if one put a gate valve or ball valve in the piping on the outlet of the pump?
     
  13. Manic

    Manic Moderator

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    As I just said im pretty sure that will work. At least two of us think it will now.
     
  14. THE ANIMAL

    THE ANIMAL Thread Starter

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    Ok Jacquesb I'f got 3 pumps 1 Quality 0.7 kw and then 2 Aquadrives (1) 0.7 kw and (1) 1.1 kw. Then to get to your brain wave I'f put in a ball valve on both sides. It is like manic said by the time the bubbles are gone there are now flow left.
     
  15. Manic

    Manic Moderator

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    The flow shouldn't stop, you will get about 90% of the total flow. Just if you put the ball valve close to the pump it would be better. If it is close to the point where the water enters the tank then the water will have a really high velocity.
     
  16. THE ANIMAL

    THE ANIMAL Thread Starter

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    Ok so I must put the valve on the outled side close to the pump as I can, is that what you say?
     
  17. Reef Maniac

    Reef Maniac MASA Contributor

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    Yes, the pump is probably cavitating.

    You can either restrict the output, as suggested by Manic, or (better option) increase the size of the inlet to allow more water to flow into the pump.

    If you restrict the outlet then you are actually wasting the pump, getting perhaps a 0.5 kw pump performance from a 1.1kw pump - not really worth it, IMHO... a cavitating pump will generate excess heat, and (I think...) use more electricity. It will also reduce the life span of the pump.

    Hennie
     
  18. Manic

    Manic Moderator

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    It will reduce the effieciency of the pump. Like you said it wouldn't be running at its full 1.1Kw. Making the inlet slightly bigger than the outlet would help. Try making the inlet as big as possible.
     
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