I have a 60 gallon tank with a ecosystem. It is an established tank of 1 1/2 yrs. I have never purchased a protein skimmer and the tank is doing fine. What does a protein skimmer do that the ecosystem doesn't do? I have had conflicting reports from different people. Some say that I definitely need a protein skimmer. Others say I definitely don't need a protein skimmer and they show me their tanks that have not needed a h20 change in 10 mths and their tanks are doing beautifully. I am confused.