th only thing that this could possibly do to a reef tank, and youd have to be very anal to do something like this, but if you had a programmable timer, you could program the moon lights to follow the course of the moon cycle and this could possibly stimulate your captive corals to spawn, as this is what happens in the reef. the different moon phases stimulate differnt corals to release eggs and sperm, sometimes in a package together, so really the 9only thing that could happen would be a natural spawning of your corals, but again, youd have to get info about different lunar phases on differnet reefs, make an average of all the data(as we really dont know exactly where many of out animals came from) and then program this into a timer to control the intensity of the lights it was controlling! definately would be interesting though!
good luck
jon