i just switched my lights from 265watt pc to 440watt vho. a week after i changed the lighting they seem to be loosing their color from a dark green to a pale greenish color. they are in the middle of the tank...should i place them on the bottom? the tank is a regular 55gal 48x13x20. i didnt think that the vho's would cause bleaching...any recomendations on what i should do?