So... since i found some local intrest in some zoas and rics, I can fit a 15g high under my existing 12 gal display, what lighting do you guys think i should go with. I might possibly be able to fit a 24 inch light but it would be crooked under there (its 23.2 inches of room in the stand) or should i go with that 18 inch t5 setup and get 2 of them (4 bulb) or is MH the way to go ( already have 70 watt retro on my 12 gal) thanks

Over that tank, I would use the 70W halide and perhaps supplement it with a couple of the 18w T5 actinics or PC actinics.

4x T5 setup should also be fine. You could even forget the actinics & do full 10,000K or possibly a 6500K or two for better growth.