making a sump flow rate question

[n8ball2013]

Im going to attempt to make a 10 gallon sump for the 12 gallon i have i have most of the stuff figured out but the flow rate is kinda stumping me. the smallest overflow box i can find is 300 gph. isnt that going to be too high a turnover rate to be effective? and if anyone can shed some light on making my own or even a smaller overflow box it would be much appreciated

 

[dmc888]

I don't think 300gph would be too much for 12 gallon. I would check the nano section to see how high you can go flow wise.
The rating for the overflow box is the maximum gph. Your fine as long as you don't go over.