Another quick SW question

[Ormarr]

I have a bit of trouble understand the drain/return part of a sump (well, not really, but I have a question about it).

Say you have a 1000gph pump feeding your return line back to the tank, is gravity alone sufficient for draining enough water to your sump or is it necessary to throttle back your return pump?

I'm just thinking a big pump might make your sump run dry...

Or is it common practice to have a pump inside your tank feeding the drain line??

Any clarification on this is appreciated.

[redbelly]

Your overflows should be designed to handle all of the water thatyour return pump provides.
Actually one overflow should be able to handle all of the water from your return pump and the second one should be a redundency incase the first gets clogged..

what size/design overflow are you using?

[Ormarr]

None at the moment.  I'm considering getting a pre-drilled 90g which has 2 holes (1 for drain and 1 for return, holes are on the back glass).  What would be my best option?

[sniggir]

ifyou do decide to get the predrilled make sure that it is a 2.5 inch or 65 mm hole.. or rather will fit a 1.5 inch bulk head that way for your drain you can ve sure it will be able to handle the flow..... I would still request 2 drains but completely up to you.... and your floor....