Aright, i just picked up an 18'' flourescant one of these for my 20g. Its supposedly better than a regular 15 watt for plant growth. Anyone have any experience with these? DO they work? if not its not a big deal, its 3.50$ at home depot. btw, it gives off a dimmish yellow light as opposed to the purple/white light aof a normal flourescent. just letting you know.