How many gallons per hour for return pumps?

Discussion in 'General Reef Discussion' started by capman, Oct 25, 2017.

  1. RSnodgrass

    RSnodgrass TCMAS President
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    Jonty enlightened me that my setup is lacking one of two features to make my pumps work as well as they could.
    1) I run a shallow sump... guessing around 9" would be better to help jump start the pump. (keep the air pocket further from the impeller)
    2) A check valve on the return to prevent air from being mixed with the pump on start up after a back siphon has started. This seems to cause issues.
     
  2. OP
    capman

    capman I contributed!
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    I'm not sure I'm following regarding the check valve. Can you explain further?
     
  3. marty9876

    marty9876 Banned
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    Well this is embarrassing... It's an Iwaki WMD 40RLXT pump not a 55... Anyways, the 40RLXT is about 68 dBA and the MD-100RLT is about 72 dBA. Readings via Radio Shack Analog meter, C weighting at roughly 1 meter. I have a calibrated microphone I can get going if you really want to get into the details.

    40RLXT is on a vibration pad, connected to spa flex line on the output and hard plumbed into the sump. Note: the 40RLXT has a offset output, slightly annoying as it's not any standard degree offset (e.g 22.5, 45, 90). It's slightly beneficence to use flexible spa flex lines I think to cut down on vibration and noise.

    100RLT is just hard plumbed into the mixing station, no efforts on sound reduction there.
     
  4. RSnodgrass

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    Bill, this type of pump or brand seems to greatly benefit from being primed fully with water to spare in height above the pump. The check valve insures that water will always be primed on the pump since my standard sump height may be too shallow.

    This will also prevent air/water mixture upon back siphoning which also impacts its ability to start working while occurring. Thirdly it gives the pump time to spool up which is apparently a feature to lessen stress on the pump.

    Alternatively I could have made the water level in my sump a few inches deeper to put the top of the pump comfortably below the water line by a few inches.
     
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  5. KJoFan

    KJoFan Senior Member
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    So...the moral of the story is that a check valve is not needed in ALL applications, just specifically to yours because of the shallow sump situation.

    Generally speaking, if the pump is well submerged, no issues with the VarioS should arise?
     
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  6. OP
    capman

    capman I contributed!
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    Thanks Marty. This is really helpful.

    Though I'm not equipped to do such accurate decibel readings (e.g. of our existing noisy tanks in the lab), this gives me a general idea.
    And it tells me that the different sizes of pump are not too radically different in noise level.

    I do note though that your smaller pump is an American made model (so, supposedly a little louder than the Japanese pumps), while the larger one is a Japanese pump. So possibly this reduces the apparent difference in noise between the different pump sizes.

    I guess I'm thinking of going with two MD-55RLT pumps on each system. So, I guess there is going to be some noise. And the big skimmer and its pumps are going to be adding to the noise.

    I don't mind having some noise in the back room, but my concern is that it not spill over into the teaching lab too much. I simply won't know how good the sound isolation is going to be until we have the tanks and stands and enclosures set up (which will be happening two weeks from this Wednesday).

    Maybe I need to get one pump and try it out before committing to these pumps completely. Bill Wann recommended an Iwaki 70 or 100 to feed the big skimmer he built - maybe I should start with that pump and make my decision on the rest of the pumps based on how unacceptable that sound level is.

    Who knows, maybe I'm going to end up going with DC pumps or something after all (and just will need to plan on replacing them more often).
     
  7. marty9876

    marty9876 Banned
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    Can you plumb the system so the overflows feed the skimmer? Much better design (grab the particulate matter before it breaks down) and less pumps is always better. I've got to say, from a redundancy and simplicity point of view having matching pumps across all systems would be great. 4x active pumps, budget for a 5th cold spare (not that you'd need it) and the core life support elements of the system would be bullet proof. As reliable and maintenance free as frankly a hobbyist system could be. Go to BRS and tell them you want 5x Iwaki's and I'm sure you'd get a deal.

    The skimmer recirc pump will be different, Reeflo with a special impeller I think. Reeflo pumps are good, lots of flow just you have yearly or every 2 year service required on the seals. Standardizing on all Reeflo's if you needed the flow is a valid move, just more service needs and keeping the skimmer as a one off isn't too might of a deal. If the skimmer was down for a week it's more or less a non event, loose the main pumps for a week and everything is dead.

    It's hard recommending old technology pumps but if the electricity usage, control-ability and noise factors are not the primary drivers (I assume absolute reliability is) then the classic AC driven pumps seem like a no-brainier to me. If the system was in your living room and a high-end tank you wanted to fidget with nightly, different story.
     
  8. marty9876

    marty9876 Banned
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    Re check valves - I think it comes down to the design of the pump how the react in low level 'primed' conditions and air intake. My Reeflo pump is a lot like the DC pumps I've used (Jebeo) with a "large high flow, low pressure" design which I think many DC pumps have. The Reeflo really hates stops and starts, if the water is still flowing backwards after a quick 10-30 second outage the pump won't start (cavitates/spins, doesn't 'grab' the water with enough traction to start). I don't know how it would respond to a check valve setup, I assume positively but would have some concerns. Iwaki pumps could care less, I've never have one not fire. I think I programmed a DEFER statement in my Apex to avoid quick start/stops of the main pump.

    Traditional con of check valves is they are a maintenance item - if the system is designed that if the valve fails and the sump overflows during a power outage, then fires back up you won't have enough water in the system and bad things will happen. Plumbed with bypass and drains an such are a great item.
     
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    capman

    capman I contributed!
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    My only real concerns are reliability (as bulletproof as possible) and noise. Conflicting needs, I know.

    Keeping complicated, delicate aquarium systems in a location away from your home presents special challenges, and as much reliability as possible is important. And fiddly pumps have often been a thorn in my side.

    Noise is only a concern insofar as it spills over into the adjacent teaching lab that will be on the other side of the display tanks. I think the enclosures being built by Custom Aquariums (with sliding access panels) will probably contain a lot of the sound. But there will be a 3 foot wide doorway between the two big systems that will go from the teaching lab to the equipment room/research room behind the tanks. There will be some sort of door (still to be figured out by Custom Aquariums I think), but it might be pretty light weight. We'll see how this all works out.

    Regarding supplying the skimmer: Bill Wann who built the skimmer recommended about 2000 gallons per hour through the skimmer. He doesn't like DC pumps (personal preference, with some good rationale) and suggested an Iwaki (no special impeller or anything - this is just to move water through the skimmer - there is another pump built into the skimmer). But I might go with some sort of quieter submersible pump instead, just to not add any more to the noise than necessary.

    I don't know whether sending 2000 gallons per hour through the skimmer from overflows by gravity flow will work. As I recall the skimmer intake is a pretty large pipe, but I won't really know until I'm able to fully unpack and examine the skimmer.

    There are far too many balls in the air right now.
     
    #29 capman, Oct 31, 2017
    Last edited: Oct 31, 2017

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