It's actually pretty cool to use it on a bottle, I was able to provide several watering options for an integration issue and it worked well with the tube in the bottle, I also plan to use them in a gravity feed system during summer and eventually in a heated, recirculating system in the winter...
The tube allows the needed air flow without water leaking out when you are filling the bottle.
I was able to put a tube into a bottle to avoid the leaking whilst filling and avoid the exorbitant price of buying a bottle with the tube already installed..but I am a pretty handy chick, lol.
Now I...