A proper aerator is vital to having a healthy pond, water garden or lake no matter what time of year it is. Use an air pump during hot weather to provide the necessary oxygen within the pond.
During the winter a pond aerator will keep an opening in the ice, add oxygen and help gas off toxins.
Any pond will benefit from additonal aeration. A pond air pump will also help the growth rate of your koi or goldfish.
Adding an aerator will also help the biological process within your pond. Biological filtration requires large amounts of oxygen so an air pump should be used.
Where is the best place in any pond system to add air or oxygen?
Directly into the biofilter system as close a possible to where the bacteria are sitting. This is why vortex filters and Japanese matting work so fantastically well together in any serious water ponds system - but only by pumping plentiful volumes of air around the Japanese matting matrix.
How much air should you add to you Koi Pond?
Add as much air to your pond as you can using air pumps and air stones to distribute the air (highly recommended for ponds that are heavily stocked). You can add the air directly to the pond, the filter, the waterfall and anywhere else you can think of. The amount of oxygen water can hold is dependent upon atmospheric pressure, salinity and temperature.
(In general terms, 40lpm per 1000 gallons is a good rule of thumb.)
Water can hold less oxygen as altitude increases. Salinity is not important for most freshwater fish producers. The most important factor is water temperature. As temperature increases, water can hold less oxygen. Most low oxygen problems occur from June through September. The reasons for this are: