[corvettephreek]

auto top off would be kinda difficult on a small tank, but certainly doable. I would have a sealed cup full of bottled water and have a peice of airline tubing on the cap. make a cradle for the bottle to be upside down, and every time you need to top it off, you just put the bottle in the cradle and wait a few seconds. or maybe a small chamber in the back of the tank where you can use the same idea alhambra uses in their water machines. where once the water reaches a certain point the bottle's "seal" on the water is broken and the water is replenished, just until the water line reaches just above the tip of the bottle. idea?