I use a simple screw bulb normal desk lamp in mine, (Clip on style with flexible shaft) bought at garage sale for 25c 3 years ago. I use a simple twist type 65 watt flourescent bulb in it and have been using it for 3 years and I grow chaeto and pods, out the wahoo with it. I started with a fist sized piece Dave at Kermits gave me and now I keep a rather large ball about the size of 2 softballs in there and pull out a fistfull at least once a week.
I have it on a timer opposite my main tank. Easy simple and cheap.