Hey guys. I have some questions about hanging height and optics. I have 24 leds on a 6x10 heatsink I'm going to hang over a 20 long (30x12x12"). I realize that's going to leave the ends of the tank rather dim while the middle is super bright. I'm ok with this and planning my rock scape to support it. Since the tank is only 12" deep I'm thinking optics are not required. If I go with no optics how high above the water should I hang the lights? Should I use optics?