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  1. #1

    Drum filter levels

    So my Drum is up and running

    However, I didn't get the height correct/perfect.

    When everything is off, the level is above the minimum mark, about a 3rd maybe 1/2 an inch. When everything is on it drops about 1/4 of an inch below the minimum mark and the clean side is about 1/4 of an inch lower than that.


    Is this fine? I'm sure I've read that others have much more draw down than this but if it needs rectified then would rather sort it.



    I'm getting much more flow than I used to, my auga 30k is running at 55%(I am going to up it a bit but need more holes in the spray bar) on its new 2 inch pipe with no inline UV. This is providing more flow over the shower than it used to on 1.5 inch pipe through a 110 uv combined with a Hailea 12000 pump that came from my moving bed.

    I can't give figures how much more, but it's a lot more as the shower is flowing more and the Hailea pump is flowing back to the pond after the moving bed now instead of the shower



    So I guess I need to know what level people's drums are showing when running, mines a Synergy 55 but any info would be handy.


    Thanks J



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  3. #2
    Senior Member Rank = Gosai Scorchio's Avatar
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    Hi John,

    It sounds fine to me. The levels will drop when the pumps are on. I have 3 20k pumps running at around 60% on mine.

    I set my drum perfectly on initial install. Water level on the max line in the drum.The levels drop by an inch at least when all the pumps are on.
    I have since added trickle in /out and use the waste outlet on the drum as my overflow.
    Now when I turn the pumps off water flows to waste instantly as the levels in the drum rise above the waste line.

    Hope this helps

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  5. #3
    Quote Originally Posted by Scorchio View Post
    Hi John,

    It sounds fine to me. The levels will drop when the pumps are on. I have 3 20k pumps running at around 60% on mine.

    I set my drum perfectly on initial install. Water level on the max line in the drum.The levels drop by an inch at least when all the pumps are on.
    I have since added trickle in /out and use the waste outlet on the drum as my overflow.
    Now when I turn the pumps off water flows to waste instantly as the levels in the drum rise above the waste line.

    Hope this helps


    Thanks, I shall run it for a few days and see. Obviously I just want it to be right, but if its not wrong then I don't see much point in changing it.

    Cleaning cycles don't seem dramatic and the dry run protection only kicked in when I 1st tried it but the pond level was way down after filling the drum, pipework and 2 blue barrels.

  6. #4
    Extreme Koi Member Rank = Nanasai NickK-UK's Avatar
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    What's not stated is that drums make the water level rise and lower when you have gravity feed.

    When the pump runs and the drum is dirty, not enough water flows through and the clean side of the drum drops - the pond level rises, and the level rises on the inlet side of the drum too. This can cause an overflow making the next step seem like an even larger drop.
    When the drum washes, the water flows through to refill the water level and the pond water level and the inlet level drops..

    So the ideal is that there's minimal drop on the clean side but the drum is large enough to cope with the flow/waste load before the water level drops on the clean side. That way the drum will not be cleaning repeatedly.
    1700 litres on 50 watts
    Planned 11,777 litres on 58 watts. 1300l anoxic, 4" airlifts, Solum 16, bio.

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  8. #5
    Quote Originally Posted by NickK-UK View Post
    What's not stated is that drums make the water level rise and lower when you have gravity feed.

    When the pump runs and the drum is dirty, not enough water flows through and the clean side of the drum drops - the pond level rises, and the level rises on the inlet side of the drum too. This can cause an overflow making the next step seem like an even larger drop.
    When the drum washes, the water flows through to refill the water level and the pond water level and the inlet level drops..

    So the ideal is that there's minimal drop on the clean side but the drum is large enough to cope with the flow/waste load before the water level drops on the clean side. That way the drum will not be cleaning repeatedly.
    Mine does this and it’s really flipping annoying


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  10. #6
    Extreme Koi Member Rank = Nanasai NickK-UK's Avatar
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    Quote Originally Posted by bigcarpchaser View Post
    Mine does this and it’s really flipping annoying


    Sent from my iPhone using Tapatalk
    It occurred me that an air lift is less likely to have an issue compared to a pump.

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  12. #7
    Quote Originally Posted by NickK-UK View Post
    It occurred me that an air lift is less likely to have an issue compared to a pump.
    How come Nick?
    Interested to know your thoughts on this as considering an full air lift conversion if I can wangle it


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  14. #8
    Extreme Koi Member Rank = Nanasai NickK-UK's Avatar
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    Quote Originally Posted by bigcarpchaser View Post
    How come Nick?
    Interested to know your thoughts on this as considering an full air lift conversion if I can wangle it


    Sent from my iPhone using Tapatalk
    My thinking on this is that the air lift has less force to apply compared to a 5+m head pump. So the back pressure of the rising pond level and the lack of pressure caused by reduction of level in the filter means there's a ramp of pressure pushing back from the pond. A pump can overcome that and therefore you end up with a low filter level but an airlift finds that difficult hence will stop emptying the filter.

    All depends on how much force the airlift can deliver.

    Not that is stopping the idea that I will still use airlifts too..
    1700 litres on 50 watts
    Planned 11,777 litres on 58 watts. 1300l anoxic, 4" airlifts, Solum 16, bio.

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  16. #9
    So it’s “oommmph” from the pump effectively not necessarily the volume of flow you think?
    Ie, 20k blasting back from a pump is less gentle than the same volume of water via air lifts?


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  17. #10
    Extreme Koi Member Rank = Nanasai NickK-UK's Avatar
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    Quote Originally Posted by bigcarpchaser View Post
    So it’s “oommmph” from the pump effectively not necessarily the volume of flow you think?
    Ie, 20k blasting back from a pump is less gentle than the same volume of water via air lifts?


    Sent from my iPhone using Tapatalk
    I think it depends on the design

  18. #11
    The airlift I’ve been playing with is the same design as twhite’s, 4”, 1500mm with an air chamber but only one tee off. All hard piped and I have to say, it really shifts some water. If I were running one as a permanent return I’d possibly put a 45 bend on the end and angle slightly down into the water and crossways to get some circulation. I think that would work plus it’s all push fit waste pipe so dead easy to mess about with.
    Holding my hand over one of my pumped lines when it’s running full bore at 20k through 4” pipework is still less than the airlift is shifting I’d say.


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  19. #12
    Extreme Koi Member Rank = Nanasai NickK-UK's Avatar
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    Quote Originally Posted by bigcarpchaser View Post
    The airlift I’ve been playing with is the same design as twhite’s, 4”, 1500mm with an air chamber but only one tee off. All hard piped and I have to say, it really shifts some water. If I were running one as a permanent return I’d possibly put a 45 bend on the end and angle slightly down into the water and crossways to get some circulation. I think that would work plus it’s all push fit waste pipe so dead easy to mess about with.
    Holding my hand over one of my pumped lines when it’s running full bore at 20k through 4” pipework is still less than the airlift is shifting I’d say.


    Sent from my iPhone using Tapatalk

    Pressure vs flow rate is what I would be interested in - if you put a partially clogged mesh over the input, does it still suck water through in the same way and reduce input head height (thus submersion level)?


    Probably better with a diagram.

    Normally there's a small increase in the pond height and decrease in chamber height caused by the airlift, the same with the pump. The flow rate is high.

    Blocked drum. The filter water drains. Increasing the pond height. The filter drains and the level drops. Air lift performance is based on submerged ratio - the less the submergence the lower the ability to lift (the force it can apply). So you have a fuller pond putting pressure back into the filter through the airlift. The decreased level in the chamber reduces equalising water pressure and reduces the airflow submergence.
    This is compounded that a sump/chamber that the airlift is typically smaller than the pond so you quickly exhaust the submergence ratio.

    The pressure in the pond therefore rises and the chamber decreases, a pump can maintain a 5.5m head with 0 flow. I suspect an airlift would fail before that unless it has a far far deeper submerged portion.

    Top - pond (left) and chamber (right) with airlift between.
    Bottom - pressure gradient between the two as the water level changes. The steeper it is - the more head height force the pump/airlift has to work.

    IMG_7898.jpg


    I agree the performance is higher in an open circuit.. just curious on the scenario where the drum is blocked which causes the yo-yo effect.. instead would we see a yo-yo in airlift flow rate rather than a yo-yo in pond level?
    1700 litres on 50 watts
    Planned 11,777 litres on 58 watts. 1300l anoxic, 4" airlifts, Solum 16, bio.

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  21. #13

    Drum filter levels

    Thanks mate...I “think” I get it.
    In my simple mind I was thinking as the drum screen blocks and lowers in the dirty side, the pump will be returning more to the pond than the drum will be flowing hence the rise in pond water height, hence the overflow.
    I’d convinced myself I’d got a leak until I sat and watched it for an hour lol


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    Last edited by bigcarpchaser; 04-07-2020 at 10:37 AM.

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