So not quite what I was talking about. This will be a true gravity feed ATO as the reservoir will sit above the tank, but will have two lines going into the water. one will be the water line and one will be the air line, both of with will go into the display tank. The "Air line" works as your minimum tank volume as it creates a small vacuum when plugged with water. The water line only runs when air flows into the top of the jug via the air line. so when the water drops below the "air line" the water line starts to flow until the air line gets plugged with water.
Think of the old cup in water trick where you fill a cup in a tub and flip the cup. The water can be raised above the body of water. If you add an air hole to the top of the cup and cover it, same thing happens. But then you open the air hole the water looses the vacuum and flows through.
so here's a basic drawing of what im trying to do.... I've followed lots of posts and know it works (tested in my laundry tub with no modifications) but don't know how to attach the air lines to the tap.
[IMG]
[/IMG]