Sump/Refuge

well i have a 20 gallon with a 20 gallon sump... your saying this is WAYYYYYY too big of a sump? im about to purchase a 300 gph overflow box on ebay...

Eshopps Overflow Box PF-300 for Aquarium Reef Tanks NIB - eBay (item 350147945286 end time May-31-09 17:05:54 PDT)

 

Yes, you will lose gph for every foot of head and every elbow(90 or 45 deg). This is where you need to calculate how far the sump is away from the DT and how many elbows you'll have. Each elbow equals to 1' of head. All pumps have a chart showing how much gph for every foot of head. I personaly like to have a "bigger" than needed pump, I'd rather have bigger than too little. You can always control the flow with a ball valve. Hope this helps. Luna