I very much like this system and have research very heavily. Is your refugium 20% of total water volume? Also they don't mention the part were your skimmer, your hands, tools, and even air are putting contaminates in your tank daily. Carbon is good but not 100%. I don't think any system truly eliminates water changes. Yes they may limit them but eventually things will be off and require a change. Alot of ppl get into trouble not reading the fine point of no "maintaince" changes and skill the $60 tests required every 30 days at start and every 90 there after