On a treadle machine I've read that aquarium tubing can be used for the belt. I figured new oxygen tubing (the pieces that go from the tank to the nose ) would work the same way. However, it seems as if they are stretching out. For three days in a row, every morning the belt slips so I cut off 1/4 inch and then all is fine - until the next day. Does anyone using aquarium tubing have the same issue? If yes, how long does it take for the tube to stop stretching (if it DOES stop stretching). If no, then I guess I won't try to use this oxygen tube anymore - I'll get some leather.