You may have stated this already but what depth are you considering putting the diffuser? What is the total size of pond? How much open water do you want/need.Will you aerate spring/summer/fall ? Keep in mind the more devices you put inline the more restrictions they cause which is additional backpressure and depending on the type of compressor some produce much less air at the higher pressure than others. A compressor that restarts under pressure (most dont) may be needed since a checkvalve may be utilized, A compressor that has an operating range for cold temps should be considered.Many are only rated to 40F for the minimum. If you use a brass "swing valve" they are very soft and will need replacing every 2-3 years. Great input by everyone so far.
