Good Pond Aeration is an essential requirement in all good Koi ponds. All Ponds need a plentiful supply of oxygen. Both your fish and the biological filter require large amounts of oxygen to thrive.

A good quality air pump such can power several air stones even at five or six feet depth. It is a good idea to place a few air stones directly in the filter system to provide oxygen for the filter bacteria as well as in the pond itself.

Oxygen will also be added by water splashing into the pond on its' return from the filter and waterfalls are especially effective in this respect.