This is my first post. I've been very inspired by this site! I used to make wine, so I made a diy co2 unit quickly and easily using standard inexpensive wine making supplies: a one gallon glass wine jug which already comes with a rubber cork with a hole in it for tubing and some tubing. The wine making tubing is slightly wider in diameter than the standard tubing that is sold with airstones at the LFS, but that tubing slides perfectly into the wine tubing and the wine tubing is tight in the rubber cork so I haven't had any problems with air leaks. I think that the glass bottles look cool in a backwoods bootlegger/mad scientist/eccentric Victorian parlor kinda way...so it elimates the need to hide the bottles and with the tight seals you don't need to worry about silicone.
I also have some 5 and 6 gallon glass carboys that I'm not using to make wine and was wondering if anyone had any ideas or thoughts about whether I could use these to make planted aquariums. These jugs are made of heavy, clear glass. The largest part of the jug is 10" in diameter and 15" high. After 15 inches the upper part of the jug slopes gently inward and upward for about 9 inches ending in an opening that is about 1 1/3 inches in diameter. These jugs also come with airtight rubber corks and tubes which could be used to input CO2 or O2.