I've read that it's normal for 1-3 weeks while it breaks in, but I also see that they sell a "bubble stop" which shouldn't be necessary if the bubbles stop on their own eventually. No matter, I don't have room in the back of my JBJ 45 for the thing even if I was willing to buy it. I installed it on April 1st, so I'm nearing 3 weeks and if anything it's getting worse. Halp. I extended the output tube an extra few inches so that it's completely submerged. Should I cut a piece of filter sponge to shove in the end? Any other tips/tricks?