The metal halides will raise your tanks temperature significantly. You will want to have it raised above and have a fan blowing on the surface of the water.

As for your plants, are you providing enough nutrients (e.g., estimative index + iron chelate) and co2? If you invest in a quality light fixture with good reflectors, you shouldn't have any problems getting the red you are looking for.

EDIT just noticed that I don't know how to read properly and that you don't have submerse plants (or water to say) so forget all of that.