Philips 20-Watt T12 2 ft. Fluorescent Linear Plant and Aquarium Grow Tube Light Bulb (6-Pack)Brightness: 600 lumens Estimated yearly energy cost: $2. 41 (based on 3 hours per day, 11c kwh. cost depends on rates and use) Life: 8. 2 years (based on 3 hours per day) Energy Used: 20 Watts Lumens per Watt: 30 Contains mercury: yes (for more on clean up and safe disposal visit: epa. gov cfl) Ideal for use is freshwater aquariums or for growing indoor plants Helps cast the right light spectrum that is needed for growing plants indoors and keeping