The bulb I use is an energy efficient bulb for floodlights, with a spiral type bulb inside. Try it for a few weeks, I notice a big growth difference after one week with it on mine. I like the fact that i won't burn my hand if it brush up against it and it reduces my heat exchange into my tank. To date, I don't have a chiller on my tank and i am trying to keep it that way. It does get warn after about 20 secs of constant touch.