lighting

Well i have a 33 gal tank.I have read lot's of info on lighting.I am thinking of going to 3 or 4 vho light balists.I think that it will work.because my tank is not that deep 18in and then i dont have to worey about heat as well.I was thinking of running a metal halide but thay are lots of$$ and you have to have a fan to remove the heat.But on the other hand thay suport coral better.and i what to get different kindes of corals growing in my tank.i wold like to get some good advice.