Apologies if there is already a thread about this, but I searched and couldn't find one.

I'm planning a 40 breeder and was going to drill it, but wondering what should I set it up for, 700gph or 1500gph (pretty big difference I know). I'm looking at glass-holes.com's overflow kits and wondering which is best.

Oh yeah, I'm planning on making my sump out of a 20 Long.

Any help would be greatly appreciated.

Always go for the highest amount you can fit/afford. Even if you are only flowing 200GPH for now, it would be nice to have the option to go up to 1500 GPH later if you ever made some massive changes to the tank.

But if you are shooting for a number around the 700 mark and later decide to run 1000GPH or something like that you'll ahve shot yourself in the foot.


Just my personal opinion though.

You do bring up a good point about flow regulation and I was planning on installing ball valves on both the overflow and return just in case I ever need to close the system (power outages, etc...)...of course I could also use that to mediate the flow. I feel stupid for not considering that earlier.

Thanks for the info mmelnick

1500gph is a 1.5" @ about 5" under the water line.
or
two 1" @ about 5" under the water line.

now the next ? is what length wier would this much flow need, and how deep do you want the water to be as it passes over the wier. what would be the maximum that you feel is aceptable for this, 1/8", 1/4"? aka flow rate @ the wier.