missed a few, from what you said there is also VHO and incandescent. VHO is similar to power compact and t-5's. It is in between t5 and power-compact in the light scale (i think) and is a popular light. They also come in blue light antic tubes. Incandescent is a worthless light in reef tanks, although you can get a cheap 200 watt incandescent bulb and say you have 10 wpg in a 20 gallon tank, the corals will die since the color of incandescent isnt what the corals want so stay clear of these.trreherd said:no, i think you missunderstood what you read. You have about 4 different ways of getting light. flourecent,t-5,powercompact,metal halide, and moon lighting. Im guessing all these different types of lighting are getting you confused, but its simple relly t-5,powercompact and regular flourecnt are all tubes and there good for a medium lit reef tank. The other is metal halide and thats for higher light demanding coral. actanic lighting is blue light(420-460nano-meter) But most other lightinhg is measured in kalvin. lower kalvin(2,000-9,000) are more yellow, and thats good for freshwater plants. higher calvins(10,000-20,000k) are more blue/white and thats good for reef tank lighting. For reef tanks the best lighting is actanics mixed with regular lighting. So you can get the flourecent,t-5, and cp in actanic or any other color you want, but metal halide only comes in 65k-20k. Moonlighting(led) is for nightime veiwing. not neccesary.