The power of the air pump model you have, will make the biggest difference of how much the bubbles come out, I think by getting the bar wet and the soaking will help the more even distribution of the air bubbles.
A long time ago I had a plastic tube type bar and the air basically came out of the 1st 1/3 nearest the air pump. It wasn't powerful enough to do a good job for the size of bar (the kind that makes a bubble curtain across the whole back of the tank).
Have you tried to use yours yet?