my 10 gal work tank I'm running stock screw in type hood with (1) 13W spiral CFL and (1) 18W spiral CFL bulb in the hood (horizontally mounted). I came to this decision after reading/interpreting the data found in the CFL PAR link in my signature... tank is about 5-6 months old with zero algae (other than some slight film algae on the glass that I clean about once a month). But I'm growing dwarf baby tears with no CO2 (I do dose flourish excel twice a week though).
edit: added a picture of my tank from 11/4/13 to show how little my plants were when I started... I have not added anything since this picture other than the stem plant in the back I replanted some trimmings a few times, otherwise its all grown in from that pic.