I could to this once in a while to keep it clean. Filter bags for this purpose are only available in the 1000s so this is also no good. Then gravity flow through this from one tank to the other. Adam, You mention a 3 micron filter but say you don't want to use a pump. But you'd be better off with a local brand, I'm sure.
Simplicity is the key note.
If your plumbing is going to hooked upto the top of the tank, ie. Have it go out horizontally. Anyhow, there are some ideas which I'm sure you can improve upon. Freeman Newton A.V.I.D. Acid Ventilation Industr. It is not possible to diagnose a finishing problem or the potential hazards of an operation via these pages.