To add another experience to all of this, I never did a gravity bag, always used a syringe. I put the end of the syringe in and filled it up, held it until it all went in. If I was in a hurry, I held the syringe as high as it would go so it went in faster. I could "feed" myself in under 15 minutes if needed and I did it in the car, at work, shoot, everywhere I needed to do it. I traveled with my cheer teams with the tube. I didn't have issues generally but WOULD feel bloated if I fed to fast. Also, never had it changed and never was told that it needed to be changed.
Minnie