matching sub pump and overflow

[unknownuza13]

I have a eheim 900 gph submersible pump that I am to use in a wet dry/sump I will be building. THe problem is the overflow that I already have is only rated at 600 gph.. I have a ball valve and everything is in place. I have already used it on a marineland tidepool sump and obviously when i crank up the pump it empties the sump in about 30 seconds or less even with the overflow flowing. I have a ball valve coming right off the pump and when I restrict the flow I can match the speeds.

My question is: I would think restricting the flow of the pump would cause back pressure or something and be bad for the pump.. But then I think why would they make ball valves if you can't use them.. Please someone give me some advice.. Thanks everybody..

 

[Ornatapinnis]

Restricting the out flow of a water pump will be fine as long as it is flowing at least 50% of what it is able to do. Restricting the intake side of a water pump often causes damage to the pump. Sounds like you are fine.....Joel

 

[unknownuza13]

ok cool thanks joel

 

[rallysman]

as long as there is a supply of water to the pump, restricting it shouldnt be a problem. If there wasnt enough flow and it caused the pump to cavitate, that would be bad. I have to restrict mine, and so far so good

 

[unknownuza13]

Hey rally whats the difference in the two.. like mine is a 900 gph pump but a 600 gph overflow even though I don't think it really is 600. I feel like I have to turn the ball valve at least half way to match it up...