so i got board and had an empty Tech CB gallon jug laying around so i decided to make an auto top off.
let me know what you think. don't mind the messy room.
I really like the design, expecially for a small tank. If you have even the 'smallest' air leak into the jug, then you will have an overflowed tank... be careful!
I took the air leak into consideration when setting the air tube so i set it a little low so it could accomodate an extra gallon of water. I havent tried it out yet but i will let you know later i am about to go get some water so we will see.