I don't use anything but friction.
What I do is this:
1. Start with vinyl tubing slightly smaller than the diameter of the hose barb so that it is difficult or impossible to push the two together
2. Bring a pot of water up to a roaring boil on the stove.
3. Place the end of the vinyl tubing in the boiling water for a few minutes until it is very pliable
4. Wearing heavy gloves (it's gonna be HOT!!!) push the tubing on to the barbed fitting.
5. If possible, submerge the two into a bowl of ice water - if not, a cold rag wrapped around will do the trick.
Your tubing should now be so tight that you will have to cut it off. In 30+ years of using this method I have yet to have one come off or leak.
HTH!