The original ATS design came about from Walter Adey.They were noisy and had some mechanical issues ,were expensive,and he held exclusive patent rights.Later, Morgan Lidster (Inland Aquatics) obtained the rights to sell the ATS in the 90's.Still expensive though.I'm pretty sure Jeremy @ abcreefs actually got a hold of an original back in the 90's....if I remember right,thats about the only person Ive ever known to have an original design and the only one Ive actually ever seen.
The current ATS as we know it now ,like the threads around here are nothing like the original design.Folks have basically taken the key features that make them work and simplified it.
The reason Adey left out macro's algaes was that they had "leaky structures".He used HA but only cultured "young turfs",and was aganist letting the algae grow and stated young turffs were much more efficient at nutrient uptake.
So basically folks now a days use a simple mesh screen and clean it every 2 weeks or so insump.Personally, if your interested check out a guy named PaulB <---screenname, got something very unique using a 4"pvc pipe cut in half used as a trough.I thought about doing something simialr to use as a full length overflow box.
Sorry for the ramble,