I everyone! I just received my new reef lighting via ebay but it came disassembled ( somewhat) without any sort of instructions- I'm guess most people are not as blonde as me and can figure it out on there own lol. It is a metal halide with led combo- external ballasts- which are what are throwing me for a loop! I know how to plug in so light works. My question is can they sit on top of light fixture, or are they best kept outside tank?