Sump and Flow Questions

[term_paint]

Ok I am just starting the plumbing and have a quick question i hope. I have two 1 inch drain lines and a 3/4 inch return. I want to have 15X Flow which would be in a 75 gallon which would be a total of 1125gph. I have two power heads which would give me a total of 480gph. This means i have to get a return flow of 645gph. Will a 3/4 inch return line be able to handle 645gph. Here is a plumbing diagram i was thinking please let me know if it will work. Low flow for seahorses. The diagram should say 4 1inch gate valves

 

[sbash]

Yes, a 3/4" pipe can support that flow. Make sure you put a valve on the outlet from the pump to allow you to control the flow to dial it in.