In a couple days when my MH come in I will be building a new canopy for my 30g reef. I'm going to have just one 175watt 10k MH for now with a spider reflector. My question is do I need to have any glass or anything between the bulb and the water? Since the tank is so small the bulb will only be about 5-6 inches above the water. I was reading somewhere that you have to have UV absorbing glass with metal halidies, but most tanks I see don't have anything between the water and bulb. Is this at all true do I need anything between the bulb and water?