i used standard 40 watt, 4 foot shop lights that you can buy at hardware stores like home-depot. they are the same length as the 75 and 55 gallon tanks. i hung 4 of them over my 75 gallon giving me 160 watts. its a pretty cheap way to go, i don't remember how much i spent but i would bet it was less than $75 -$100 for the shop lights and the bulbs. home-depot always sells plant growing bulbs for a pretty good price.