I saw your post and just wanted to ask how the ATS is doing for you? I have about the same size set up, 350 gallons and just finished cycling it. I am looking at algae scrubbers on the market. May I ask what ATS you chose, how it's doing for you and if you like it?I just added an ATS to my system(210 main display w/350 total gallons water). My understanding is that hair algae can out compete chaeto keeping nutrients down and hair algae out of the main display. I guess we shall see.
But the question of what is best for you might just be a matter of some trial and error. There are many successful tanks with a myriad of different filtration methods. A fuge with chaeto is a good place to start because it is relatively simple and low cost.

