I've seen these glass enclosures for HID lamps at hydroponic stores and the main advantage (as I was told by the informative staff

) is you can divert majority of the heat from the lamps before it affects the temp of your room (water in tank). These enclosures were made for the 1000W lamps so they are a little bigger than the 250W that I am planning to use. You can also attach a reflector on the aluminum ends.
I know that MH lamps operate better when hot but would it make a big difference if a small fan is used to slowly exhaust the heat out the other end?
Does anybody know if this type of equipment will be beneficial for a reef tank
