Posted By ThyRaven on 08/30/2012 11:07 AM
I'd use the 3 on the 40 and get another one for the opposite side. 3s are 750GPH if I remember right. I have a 3 I'd trade ya for the 4 if you still want to use the 3. If not what do you want for the 4?
Id trade it really for anything... it has a brand new impellar also