How much light is required??????

[The Grizz]

I was hoping some one could tell me how much light is required for a tank with a depth of 18" . I am planning a canopy above the tank about 6 - 8 " so I can get into it easily. Need some idea of what to do. I think it is to shallow for 250 MH, could I go with all T5's and if so how many 54W T5's would I need.

If you have seen my 155 Bow Front build and coral pic then you have an idea of what I have for coral and lighting in there. The new tank is going to replace this one and I would like to use as much of the lighting that is in the 155 on the new tank ( 96" x 22" x 18") but I think the MH will be to much. Please let me know what you have on your tank if it is shallow or if you are a lighting guru tell me what I need.

Thanks to all in advance.