I've not done what you are asking, but I used a muffler on my CPR Bak Pak skimmer that I use with my 40 breeder. I took an older prescription bottle, removed the labels, drilled a hole in the bottom of the bottle and another on the lid. A tick smaller than the tubing. Then ran the tube from the skimmer's pump into the bottom of the prescription bottle. I then added 1 or 2 cotton balls to the bottle, arranged them on the bottom but with the tubing open to air. I then took a foot or two of the same tubing and placed it through the lid / top, again adding 1 or two cotton balls, then closed it up. It acts like a muffler on a car if you will. If you are worried about bugs getting in this would be one way to at least trap them. Unless you mean on the outside tubing in which case you could just use hose, floss, cotton, etc.