What's the difference between PC and VHO lights?
These are differnt types of florecent bulbs. VHO
bulbs look like standard florecent bulbs except they are made special so they can be driven by a special VHO
compatiable ballast. The net result is a much brighter output. For example a 4' NO
florecent bulb is rated at 40W. Where as a 4' VHO
bulb is rated at 110W.
bulbs appear like thin florecent tubes except they are bent at one end and only have a connector on 1 end of the bulb. These have equivlent if not higher output than VHO
bulbs for the same lenght. For example a 3' PC
bulb is rated at 96W. If we calculate that out to wattage per foot (im really shooting for the moon here) then you can see the 3' PC
bulb has a wattage of 32W per foot where as the 110W bulb is at 27.5W per foot.
Both require specific ballasts designed to light the bulbs properly. Ice cap makes a very high quality ballast that will acutally lamp either or type of bulb.
Is there a listing somewhere of what corals / inverts and what light requirements they have?
Yes and no. What kind of list are you looking for? If your looking for like a char that shows one side having a list of common aquarim corals and then next to them a minimum wattage or type of light rating I dont think that exists. But if your looking for a reference of coral and light suggestions then you can fidn that in the book Aquarium Corals. You can also find that referenced on an individual coral basis on the net.
If you have a list of corals your interested in we can suggest differnt types of lighting.
Will lights too powerful damage the fish in the tank already?
No. Remember these fish's natural habatat is the natural reef in the tropics. Toward the tropics the suns rays are most direct so its very bright naturally. This is why we need the high output lights. The fish wont be bothered by the higher lights. Infact they will proably have a better aperance to them since the higher output lights and any actinic light you put on the tank will bring out the fish's natural colors.