View Full Version : sump pump question
bill37
12/13/2006, 09:10 PM
I have a 90 gal with two corner overflows. 1" pvc. I have a 20 gal sump. There will be no skimmer in the sump I have a HOB I am going to use for now. What external pump should I use for this size of a sump?
lecher
12/13/2006, 09:36 PM
I'd expect 500-600GPH tops(after head loss), given the size of the drains and account for build up inside the drains over time. Just be sure to install a valve on the output side of the return pump so you can throttle the flow to suit your needs(capicity of drains, noise, etc.). I would buy pump just slightly oversized and throttle it back.
bill37
12/13/2006, 09:42 PM
Right now I have a Gen-X PCX-40 Pump . I am getting a lot of bubbles even with baffles installed. If I throttle back will that damage the pump?
sjm817
12/13/2006, 09:45 PM
With a 20G sump, I would keep the flow low. Maybe 300 GPH or so.
lecher
12/13/2006, 09:45 PM
No will not damage pump. Done all the time. Be sure to check all fittings on the SUCTION side. Small pin hole leaks will produce copious bubbles as well.
tylorarm
12/13/2006, 09:46 PM
You're generally aiming for 3-5x flow of water in main tank according to most of what I've read. Thus, if have 90gl display would do 270gl to 450gl. You can get bigger and turn back flow on output of return pump, not input (can cause cavitation). Sounds like it might harm the pump but Sequence maker says it prolongs pump life and has lower power consumption, go figure. More compelling to get a bigger than needed pump if you think you may upsize display tank later. Flow would also depend what you're using sump for, if rocks or partitioned refugium etc. I see you have no skimmer which is one of the main uses.
tylorarm
12/13/2006, 09:50 PM
Check where you're bubbles are coming from. If getting sucked up in the return inlet, might want to add a filter sock or something to tone bubbles down. If water looks clear of bubbles near inlet check plumbing source of air.
bill37
12/13/2006, 09:57 PM
The bubbles are first being pushed into the sump. I have filter socks on the pipes. They have helped a little. The water moves through baffles and then through some LR and then into the pump to the tank. I can see the bubbles in that last chamber. I thkni it is because the sump is so small and the pump so powerfull. There is not enough room for them to break down. Would more LR inthe last chamber help?
lecher
12/13/2006, 10:01 PM
I'd throttle the pump back and/or tee off some of the flow of output side of the return pump with another valve and pump this water back into the live rock area. Thus decreasing the over flow amount and still having lots of flow in the sump for the live rock.
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