Fish and other pond life need oxygen to live and remain healthy. Beneficial bacteria inside your filter also require oxygen to break down toxic fish waste. Aeration of the pond is particularly important in warm weather when the water holds much less oxygen, and also at night when oxygenating plants stop producing oxygen and start using it.
Aeration is critical for good fish health especially during the warmer months. We like to install several air lines into the pond, each with one or two (and sometimes more) 12 inch quality airstones. We have even selected air stones with rubber bumpers to eliminate the rough surface of the airstone coming in contact with the pond surface. The rubber bumpers keep the stone surface off the pond surface. Several air stones spaced properly on the pond bottom insure excellent oxygenation.
Here are a few pictures of the air pump and air manifolds. The air manifolds are available with any number of air outlets. Each outlet can be regulated by its corresponding valve to insure even air dispersion:
Aeration is one of the most cost effective improvements you can make - your fish deserve it!