You bring up a good point. I have been told to use both, in fact someone has chaeto and an ATS. Your idea of the ATS draining into the return is great, I will make that change. I dont know how well having the fuge being fed directly from the DT is going to work, you need a flow that will tumble the chaeto and not sure if the drain will be too much or not enough... The other thing I am debating is using a filter sock. They help trap dirt, but take pods with them, which is something I need for a mandarin.