Overflow Questions for Drilled Tank

[pwmin]

I recently acquired a 300 w/ an overflow box. I was trying to get by cheap and made my own bulkhead fittings. They are working, but I had troubles getting enough threads on them and I'm constantly worried by them. Here's the thing: I used electrical conduit for the overflows and the size turns out to be 2" pipe on the drain and 1.5" on the return. If I use the bulkhead fittings from MarineDepot, the pipe size will be brought down to 1.5" and 1". I plan on building a sump and running 2 x 1000 GPH pumps. According to the sticky, one 1.5" can flow max of 1350 GPH. On this type of setup, is it necessary to have each drain flow what the pump(s) will flow or is it not? Can I get by with 1.5" and 1"? Will a 75 gallon tank be large enough for the tank and for 2000 GPH?

 

[Pharaoh]

In theory, yes. You would want each single overflow to be capable of handling all of the pumps. You would be looking at having about 1000gph worth of flow on that tank. 2000gph would be a bit much for 1 1/2" overflows.

 

[pwmin]

What if I add a DIY overflow in the box so if either clogs up, there will be a backup? I will feel much more comfortable if I get real bulkhead fittings on there.

 

[hillbilly]

It should work. I have a 240 gal. with a 55 gal. sump, 2- 1.5" bulkheads with 2- 1" returns, with a 950 gph pump on each return. You can always put a ball valve on each return line to throttle back the pump if you need too. If the homemade bulkhead fittings made me nervous, I would definitely change them. Heck, you can get 1 1/2" bulkheads for like five bucks and change at JEHMCO. By the way, it would be highly unlikely that a 1 1/2" bulkhead would ever clog up.

 

[pwmin]

Is an FX5 and 75 gallon sump running 2000 GPH overkill (or is some of it overkill and some underkill or all not enough) for a 300 that will eventually have a pretty heavy stock of fish that create heavy bio-load?

 

[hillbilly]

With a 75 gal. sump filter, there is no reason why you can't put enough high quality bio media in there to handle any load you would put in the tank. Nothing against a FX5, but you shouldn't need it. It would probably only serve to be a pain in the *** on such a tank.