My favorite item isn't livestock, it's an ozone generator. There are many arguments as to whether or not they have a difference in a reef system. What I can tell you is that I seem to produce more and thicker skimmate, my polyp extension is better, my water is clearer, and my livestock seems to be a bit happier. At one point, I was considering breaking down my 375+ gallon reef and sold my current ozone generator to another WAMAS member. He had it for about 2 months and during that time I experienced a severe degradation in water quality, coral growth, and general reef health on all accounts. I was able to acquire my ozone generator from this WAMAS member after a short while and I'm glad I did. After this period, I decided to re-invest myself emotionally and physically in my reef and was able to re-acquire my ozone generator. From the point that I reactivated the generator in my system, I experienced a distinct change in water quality. The first indication was having to clean my skimmer 4 times within 3 days. There was no change to any other parameter in my system but the addition of the generator immediately began to pull more DOM from my tanks. They are a bit expensive and even if they have the placebo effect, I will never run another system without the additional benefits of ozone. That's my two cents....