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 siphon goes faster due to a higher supply and it equalizes.
is Small Polyp Stony "Coral". Its the type that needs alot of light compared to other types of corals.
This is a picture of acropora.
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.
If you run all 800 GPH
that will be alot in my opinion. Unless you want to do a tank full of sps
, then run it lower GPH
and have 2 or 3 powerheads, a few to keep the top level high flowing.