You need a full spectrum light to support plant life. These guys don't need heat, so instead of a tube type bulb, you need a compact florecent. Streingth depends on type of enclosure. If it's small you might he able to use a 2.0, but these bulbs go up to a 10. The bigger the bulb the more heat. For my 10 gal vertical conversion a 2.0 gives me 3 degrees of heat. In winter I will go up to 5.0.

Ps. Mine is a 13 watt, they do make a 25 watt 2.0 also.