Funny how opinions work. Most who have them swear by them and those who don't, say they aren't necessary. I did not run one on my system for the first couple of years, but then I added one. I for one believe in the benefits of them. Not one single outbreak of a fish disease after adding it, even when adding 6 Tangs at once. I also believe the water is clearer. I run mine 24/7 as well. There is a lot of evidence that points towards the benefits of them. Anything that can possibly make my tank more stable and easier to maintain is a plus. My suggestion is to try one for a year and then see for yourself. Just be sure to get one powerful enough.