If you are worried about spawning, buy the simple moonlight set without the timer unit. I have bought the moonlight DIY
products from this place, and when I put them together it worked great. I think that spawining is fine in an aquarium, if you have proper filtration it should be nothing unless the tank is a nano or really small. The other option for moon lights that I have done is to buy a packet of 20 LED
's off of eBay and wire them with resistors from Radio Shack and a power adapter from a cell phone. If you really want detailed instructions, you can buy them form the Lunar Tracker site. Good luck! Moon Lights are Great!