I have a 16x16x16 acryllic cube with a flat acrillic top so I went to the lfs and paid 19$ for a duel led actinic moon light which I taped to the acrillic lid. OMG how cool. I have a 150w metal halide 20k light hanging from ceiling so when it went off the tank was dark. All my tiny sps frags and my orange riccordia are so glowing plus there is plenty of dark behind my rocks for sleeping fish, so cool. This hobby can be cool sometimes lol.