I've had a couple different ATS. I think every tank should have one. Besides the nitrate and phosphate removal they grow pods like crazy. My current system has a 210 gal refugium, an ATS, and no skimmer. A skimmer removes the waist before it is processed by your bacteria. An ATS removes the waist after your bacteria has precess it. One big difference between your ATS and refugium is that The ATS uses CO2 from the air, and your refugium uses CO2 from the water. More info than you probably wanted but thought it might Help.
Something that sometimes gets overlooked is reactor issues. Your reactor if you have one will process any waist that Makes it into it really fast. This can overload your tanks ability to deal with it. Then the algae is happy to use It to grow. if you can pre filter the water going into it and Change the media regularly it will help. On aquariums with an ATS This isn't as big of an issue because that's the whole job of an ATS. I run my reactor output Right into my ATS.