Am sure all of you will not believe this but: Two aquaintences that I know very well have two of the most incredible tanks with every kind of coral, hard, soft, stoney, and they have power compacts with no additional MH's. I beg to differ on the price of MH"s. They are much more expensive than any other system and for many cause major heating problems which of course you then need to purchase a very expensive chiller . I just ordered a power compact system which works very well for others who have great success. Cetainly hope I do. There are many more reasons for major successes other than just lighting, but it is a biggy! At the moment I am fighting phosphate and nitrate problems on other of these forums, so that hopefully will be taken care of as time passes as I undertake the necessary changes. A change in MH's when they burn out is another much larger expense than a bulbs for the compacts. Of course I don't know that MH"s can't be bought wholesale either. I will admit there is one very important thing I don't know, because several people have told me that MH last much longer than any other light. If that is so, then in the long run, it would be a better way to go than any other, if you want to have some of the more difficult anemones and such. Maybe they can. It really depends on your budget and what you can afford to maintain. If I had 600.00 dollars I probably still woould have gone with the compact because how do I know if when the MH burned out, I would have enough to cover the cost. Rather go with something I know I can afford any given time. Good luck!