If you want to do PC like Tim said, wait next year and get T5 bulbs.

My old 29 with PC:
http://www.swt.edu/~xp42012/2002/june-02-29gallons.jpg
http://www.swt.edu/~xp42012/2002/june-02-29gallon.jpg

and my older 29 with 65K MH:
http://www.swt.edu/~xp42012/2001/29gallon-takendown.jpg