They are in trays in about 2" of water within maybe 8" of a 250 watt 6K GE bulb and maybe 12" of a 400 watt 12K Sunburst (don't like any of these bulbs but am going to use them up first). The ballasts are the ASM "green HQI" ones, both 250 and 400 watt versions.
I don't really feed anything. Just whatever the tank produces.
The tank is bare bottomed, excessively skimmed (ER 8-2), intensely lit (2 -250 and a 400) and heavily circulated (2 -6000 and 2 -6060 Tunze Streams). It's dimensions are 30" X 30" X 24".