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  1. #1
    Senior Member Rank = Yonsai Bonsaijohn's Avatar
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    3 inch pipe. / input v output = headache

    I’ve had a headache for a fortnight now trying to improve my filter . Basically I’ve got 3 bottom drains on 3 inch pipes plus a skimmer on a 3 inch pipe all going into a discharge chamber . My pump is a submersible atman 25 which pumps out 25000 ltr per hr with a large Venturi on it . As soon as I take off the Venturi to run the pump at max ,the first chamber drops and subsequently by the time it gets to the last bay it dropping below the pump . I tried taking off the skimmer head giving me 4. 3 inch pipes going in but it doesn’t help much . All the pipes are clear and the transfer ports have all been enlarged to cope with the flow . I reckon the Venturi halves the output and the object is to not use it . Advice needed and some paracetamol please John



  2. #2
    Extreme Koi Member Rank = Supreme Champion john1's Avatar
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    Hi John, I would have thought 3x3ins pipes would be big enough to keep the first chamber full and you say there is no blockage,is the dome on the bottom drains high enough to let enough water through?should be 1/2ins or the thickness of your finger,maybe you need to go for a swim to check, your water is warm enough.
    My skimmer doesnt pull very much but that shouldnt be your problem,if it was the last chamber emptying i would say transfare ports not big enough,would there be a build up of dirt in the sump of the drains?

    Sorry i cant help any more,i would pull the top of one drain off so no restrictions and see if that helps then you would know.
    John

  3. #3
    Senior Member Rank = Yonsai Bonsaijohn's Avatar
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    I’ve taken off all the tops on the bottom drains . Headache

  4. #4
    Extreme Koi Member Rank = Supreme Champion john1's Avatar
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    That one would be doing my head in John.
    John

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    Senior Member Rank = Yonsai Bonsaijohn's Avatar
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    I purge the drains every week when I clean the filter and there certainly seems plenty of water coming through , nothing to make me think there was a blockage . The pump return is 2 1/2 inch so thinking of fitting a valve and taking off the Venturi , think I’ll get more return that way

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  7. #6
    Extreme Koi Member Rank = Gosai kelv0102's Avatar
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    Have you tried looking up the flow rate for the pipe you’ve used including the length? I am assuming when you open the valves to each one separately your getting a good flow? Now silly question have you checked the level of the filter water line with the pond? Reason I ask I have the same problem as my filter is about 1/2 inch to high and if I don’t have it filled to the correct level it starts to run dry as such! Have a double check it’s very frustrating!


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    Senior Member Rank = Yonsai Bonsaijohn's Avatar
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    Hi, yes I get a good flow ,how do I look up the flow rate for the pipe

  9. #8
    Extreme Koi Member Rank = Gosai kelv0102's Avatar
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    Quote Originally Posted by Bonsaijohn View Post
    Hi, yes I get a good flow ,how do I look up the flow rate for the pipe
    You should be able to get a materials data sheet from the supplier which you will need then look up a flow pipe calculator on google.

    I would be inclined to double check your levels first as the restricted flow your putting on is making it work. Taking your good flow as mean the pipework is full when discharging. It’s a simple test over fill the pond till water comes through the little hole on the skimmer and try it you’ll soon know.


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  11. #9
    Extreme Koi Member Rank = Supreme Champion john1's Avatar
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    Good point from Kelv to check the levels.

    At what point do the pipes enter the first filter?
    If near the top the pressure would be lost slightly better to enter near the bottom and as deep from the pond level as possible.
    John

  12. #10
    Senior Member Rank = Yonsai Bonsaijohn's Avatar
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    At the bottom

  13. #11
    Senior Member Rank = Yonsai Bonsaijohn's Avatar
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    Sorted , not the best scenario but it works . I had a spare 3 inch pipe coming thro the pond wall , so taken it up to 4 inch and connected it into the settlement chamber . Everything is working fine and the difference in flow is amazing, the Venturi must have been slowing the pump down more than I,d thought

  14. #12
    Senior Member Rank = Yonsai Bonsaijohn's Avatar
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    Return now without Venturi at 25000 ltr p h
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