I recently spoke with a guy who has been reefing for nearly 14 years and had some very impressive live-stock in his 245 g custom in wall tank. Among reeefing, in-door gardening sparked his interest several years ago. When questioning him on his choice of lighting he told me he used to be a strictly metal hallide fan until he found and bought high pressure sodium lighting. He said since his plantlife responded so much better to these bulbs rather than MH he tried them on his reef and hasn't used MH since. Is there any merit in what he is saying? I have yet to come across anyone posting the use of High pressure sodium bulbs so I have no idea! If any one has heard about this let me know. Also; instead of spending hundreds of dollars on a 275w Mh system, you can buy Sun System hydroponic green hous grow lights for much less. The maximizer system with 400w MH, x-ballast,and adjustable maximizer reflector tp spread the light in your tank for only 129.99. a 1000w MH system goes for 199.99. Are these the same MH's used for reef tanks? hope so (MUCH CHEAPER)Check out this sight and let me know...http://www.hydroponics.net/