About 4 months is my time frame😊

I have 25" connected to a11" with no problems ...just don't have so much that it kinks. I used to run a 50" and kept running into that problem. I change it when its starts getting hard...maybe every 3-4 months for me.

I meant tubing not tuning, I currently use 25 feet green tubing and then I think it's connects with my other 4 ft one

2 Weeks Said my O2 company I ware them till they twist on my nose or get to looking nasty

Did you get a booklet with your machine ? Or call the company you got it from they can tell you anything you need to know.