More like a gph of drain question but it's for my new sump refuge setup. So I have a 1100 gph return pump. I have 2-10g tanks one for skimmer and what not draining into another 10 gallon. ( 2-3/4" drains) then pumped back up to the display. Question is how many gph does a 3/4" drain via gravity? And via syphon? I'm plumbing it tomorrow and want to make sure it will handle the flow.