The beneficial and essential bacteria which colonize our bio-filters can take many weeks or months to develop and take hours (or even minutes depending on our level of negligence) to destroy.

First, a brief recap for the beginning koi (or any fish) keeping hobbyist: Koi respire and excrete small amounts of ammonia into their watery world. This byproduct of their life cycle is harmful or fatal to them if not removed in some manner.

Specialized bacteria which develop and inhabit surfaces within the water actually digest and break down this ammonia into nitrite which is further broken down by another type of bacteria into nitrate which is far less harmful to your fish and actually beneficial to the plant life in your pond. We koi keepers usually stock higher densities of fish in our ponds (betcha’ can’t keep just one) than Mother Nature does in a natural pond so we supplement this bacteria’s potential with the surface area provided on the media in our bio-filtration systems. These bacteria need water, oxygen and a source of food (a proper amount of ammonia) to survive.

This year, Barry and Susan Hixson, with the assistance of Indigo Ponds (blatant self-promotion!) Expanded and upgraded their backyard pond. While the fish were temporarily housed in show tanks, Barry cleverly rigged a temporary circulation loop from the tanks through an existing from the tanks through an existing Aquadyne filter and back again. A separate 50 gallon bio-reactor type filter could not easily be incorporated into this temporary life support system. An air supply was kept running in the bio-reactor for oxygen, but without a food supply (the fish’s ammonia) the bacteria in this “off-line” filter would have perished during renovations.

We elected to keep this filter active by ‘feeding’ it. Common household ammonia (without any surfactants or additives) was the food supply. Susan took a one gallon sample of the filter’s water and added enough measured ammonia to bring the percentage of ammonia up to one part per million verified with an ammonia test kit. This amount was multiplied by the number of gallons in the filter and added to the filter (in this case, a total of twelve cubic centimeters of ammonia as measured with a syringe).

We gave the filter 24 hours before retesting. No ammonia was present after 24 hours so we added the same amount again and checked after 12 hours. Again the ammonia had been consumed. We added again and checked after 8 hours and all the ammonia was gone. The filter may have converted the ammonia in a shorter period of time than our monitored results proved but we were very busy working on the pond renovations and were satisfied with our results.