I finally got around to putting an ATS on my tank 3 weeks ago. Just harvested a pile of algae off it tonight. In those 3 weeks I have doubled the amount of daily food I put in the tank, run the skimmer 6 hours/day instead of 24/7, and removed the lighting from the chaeto in the old fuge. Nitrates & phosphates are undetectable, algae in the display tank is almost nonexistent, fish are fat & happy.
An ATS is the cheapest & most effective thing I've ever done to improve water quality. I wish I had built one sooner.