Im currently setting up a 40 breeder for hopefully a small bullhead. The substrate will be pool filter sand. Will the AC70 be enough. Or any other suggestions. I need a pretty quite filter due to its location.
With regular feeding and water maintanence you will be fine. That's a 300gph filter across a 36x18 area. I will warn you that sometimes the plastic trim on tanks with that footprint is thicker and the AC70 may not fit correctly. I'm sure others will tell you that you need at least an Fx5 and Ac100, but that filter will work with regular maintanence.
Ok thanks, is there a way to Rig I up so the trim is no in the way. If this doesn't fit what filter would you suggest. I could rig or a sump but I hope not to have to.
The ac70 will fit on top, it just won't slide down correctly. I had this problem with a 65g (same 36x18) footprint and a 50g breeder. I'm not saying it won't fit for sure, but good chance it won't. You could always spend $20 more and get the 110, or look into another hob filter
You can always save the receipt if you're buying new and just return it. Again, you won't know until you try. I'm not sure if all tanks with that footprint have the same bracing or not.