match55
Aquarium Advice FINatic
You dont need to use all 800GPH of it. It will only go as fast as it gets water. The part in the tank is where water is taken in. When the pump moves faster the water level is higher and thus more water in the tank filling the overflow box. The syphon goes faster due to a higher supply and it equalizes. And SPS is Small Polyp Stony "Coral". Its the type that needs alot of light compared to other types of corals. Pvc is very simple to use. Simple measure about the distance form the overflow down to the sump, then cut. Measure again, cut, glue and tada.
hehe u editted your post, I got it now.
so the overflow box is more likely depend on how fast the return pump move the water up to the tank, am i correct?