Need sump suggestion

[smilodon]

I want to build my own tank system.

Display tank: 30 or 35 gallon, maybe drill hole or just using overflow box.
I don't about overflow box, CPR CS Overflow Boxes is good or not?
Will it start by itself if I get power back on after the power failure?
If I want to drill holes, what size of the holes do I need? What size of the
tubing and bulkhead?

Sump: 10 gallon. It's about 4 feet long from return pump tp reture nozzle to the display tank.
How much is the water flow I need from pump. 300GHP is enough or not?
How about Eheim 1250 Pump?

here is the sum design. which one is better? Protein skimmer should locate before refugium or after?

I never build sump before. All I own is the Biocube 14. So any suggestion will be appreciated.

 

[boehm742]

Attachments arent working for me, but i used a cpr overflow with the tom aquatics lifter pump, its worked well for me even through power failure. You shouldnt have a problem unless your water level in the sump is to high and wont account for the additional water in event of power failure. Im using a mag 7 for a return but ive got a 55g tank and 20g sump/fuge.