"I use these in conjunction with the larger bubble bars. In my 125gal tank, I have the bars in the back and these located mostly in the center in various places down the 6ft length of this tank. It creates a neat effect when you want something more than just a wall of bubbles in the back. I can get narrow columns of bubbles to help accent cretin décor like large rocks, plants, and drift wood. Adjustable air valves are a must for this trick. I have five of these with different outputs for the overall best effect. To help keep them in place, I “glued” them to the bottom glass with a small amount of silicon. Then I use tiny drops every 10 to 15 inches to keep the air lines in place. And because they’re under an inch or more of rock, I don’t have to worry about them getting clogged with allege and thus needing replacement. Also, having them under the rock makes lager, slower moving bubbles that look better and make less water splatter at the top of the tank. (Same goes for the bars in the back) As far as breaking goes, I haven’t uncovered them in over 8 months to even look. And of course I’m carful when I get the grave vac close to them."