There will be alot of opinions on this, so here is mine. I run a U.V. (Coralife 18w) 24/7. Since I installed it a year ago, I have not had 1 ich outbreak and algae has been kept at a minimum. The bulb is at 8000 hrs right now (The end of its lifespan) and I am starting to see a little more than normal algae. I have never seen anything negative with anything in my tank...I have not lost 1 fish since installed, and corals are all thriving, hard and soft. So in case you cant already tell, I am a fan. Now, time to order my new bulb!!