NO fluorescent do only last about 6 months. But PC can last till they die. They loose some brightness after a few months and I have read that PC should be replaced every year or so but I have bulbs well over 2 years old now without any problems. I have read where some people have used PC bulbs longer without any trouble. I have changed all my tanks over to PC. The only time I change bulbs is to try different K bulbs or they die. Its cost more up front but replacing NO bulbs over 6 tanks was a real cost/year.
Hawk |