Can you please tell us what size the aquarium is? and what substrate you have in it?
120gal 48x24x24
80:20 Eco-Complete:Tahitian Moon Sand
Do you have two filter returns on left and right?
Yes, one return on each side. Tank is an AGA Reef Ready, but I did not use the standard AGA Overflow kit, constructed my own standpipe for drains and returns are Lineloc.
if it's not too much trouble, tell us more about the MH lighting you're using.
The fixture is AquaMedic's AquaSpaceLight 2x250W, doubled ended 5500K bulbs.
I have a journal, but I really need to write it up better and get it on-line. Someone in chat has been harping on me to do so, possibly this weekend if the weather is foul.