Another note. As Anthony said, PC lighting is terribly inefficient. Also keep in mind that more and more vendors are discontinuing PC bulbs, as they're becoming obsolete. Before too much longer, you won't be able to find replacement bulbs! Time to start looking for an alternative lighting fixture, IMO. Unfortunately, this is a bit difficult, with the smaller Nano systems, without having to make the leap to MH! I'm in a similar boat, right now, as I want to replace a 150MH Sunpod, over Angie's 24 gallon Aquapod, with a T5 fixture. Unfortunately, there are very few quality 20" T5 fixtures, and even fewer quality bulbs, in the 20" length, to choose from.