Tried the 175W MH in a parabolic type reflector over the sump with a 4K grow bulb to get an idea. Assuming SE marine bulbs can be mounted vertical so think will just go with this reflector. Probably will go with a 10k bulb.
Area in sump is 21x17x10"d (15g) and flow through section is about 1000gph so turn is ~67X. Bulb is 8" above water and water is 10" deep. Guess my biggest worry other than the cops banging on my door will be nuisance algae growth in the sump.
