[mbbuna]

if you look at a PC light bulb,lets say a standard 96w. there about 3' long,2- 5/8" tubes next to each other. that's about 6' of tubing being lit buy 96w,that works out to less then 2w per inch.thats not a lot of energy to drive the light through the air and into the water then through the water. and were not even talking about how much is lost do to reflectors, bounce back off the water ect..

now lets look at MH, all the watt energy is coming from a 1/2" point source. the light photons(this is what corals and clams use)are being fired out with a lot more energy behind them and can drive down through the air, water and give that energy to the zoox in the clams and corals, where as with PC and such a lot of the energy is lost just trying to get there.

also MH can do this for a lot longer then PC's.MH bulbs can last for 1 or 2 years before they lose there intensity, Fluorescent last about 6 months