References - Air Diffusers
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Air Diffusers

Doug Kevis



Many people have asked me how I make wooden air diffusers for my large (4' to 5' deep water column) Counter Current protein skimmers. The reason I make them is that I could not find a convenient source for a 6" long diffuser, and the 3" long diffusers that were readily available did not create enough bubbles for the skimmer to work properly and if I used two 3" diffusers in each skimmer, my monthly air diffuser bill would be over $10.00. So, I was forced in make my own if I wanted my skimmers to function effectively. The following plans are for a 6" long air diffuser, but they can be made to any reasonable length.


An air diffuser in a protein skimmer must produce large quantities of the smallest bubbles possible for the skimmer to effectively remove nutrients from your salt water. The type of wood becomes important due to the required bubble size. My research for the proper materials led me to lime wood as that most commonly used. However, the search for lime wood in the Pittsburgh area proved fruitless (no pun intended) so I had to search for an alternative.

Other woods that have been suggested include Bass wood and Oak. I had an e-mail exchange with Albert Thiel recently, in which he told me that he tested several types of wood and found that oak produced much smaller bubbles, but required a stronger air pump, so I will experiment with Oak in the near future.

The second most commonly used wood was basswood, and I was able to find it at the local Woodcrafters supply shop. I purchased a piece of 1" x 6" x 6' long basswood board for about $7.00. Look for a real fine end grain on the wood. The finer the grain is in the wood, the smaller the air bubbles.

Important: The length of a diffuser can only be made to whatever the width of the boards are available to you, since they only function when cut across the grain of the wood, not along the length of the grain. The widest basswood board I saw was 8", so from this board I could make a 7.5" long diffuser.

The only other component necessary was a plastic nozzle to attach the airline tubing to the diffuser. Unable to find an easy source for these, I began to recycle the old ones I had removed from the old Coralife and TFP air diffusers I used to buy. These have a pipe thread on the end that allows them to be easily installed and removed from your diffusers. I have tried other types of airline nozzles, one in particular has a plastic insert with a rubber stopper on it that I found difficult to install and reinstall.



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