The air manifold is very important for two reasons. It gives you the ability to send air to various areas within the pond or lake and allows you to vent off potential back pressure. Connect the outlet of your air pump to a 6 or 12 way manifold. The manifold has valves which control the outlet of air to your air stones or diffusers.
If you live in area with drastic temperature changes, be sure to build your pond deep. Deeper ponds will have more stable water temperatures. The temperature in shallow ponds can fluctuate radically in spring. These fluctuations can make it difficult for beneficial bacteria to colonize.
