Peaceful World Conversations

Currently I am experimenting with aquaponics as a means of producing food that has a lower level of embodied energy and that can be grown in a degraded environment like a larger city.  I have a system that is built but I'm in the process of expanding the grow space.

  Aquaponics is the union of aquaculture and hydroponic systems.  Hydroponics is nothing more than growing plants in a soilless environment.  The soil in urban areas are often a large problem for city farmers.  We have areas that are brownfields where the thought of growing food would be absurd or dangerous and we also have very large areas that have been permanently degraded through the use of asphalt and concrete.  Hydroponics fits in well with these conditions because it removes the largest obstacle which is the soil.

  Aquaculture solves the nutritional needs of hydroponic systems which are often very sensitive to the conditions of the water that they grow in.  When fish are added to hydroponics we get close to a closed ecosystem.  By feeding the fish we allow them to grow and in doing so they output ammonia as waste.  The waste is then fed to the grow medium which provides a large surface area for bacteria to grow on.  There are two types of bacteria that aid in the processing of this ammonia so that the end result is nutrition that our plants need to grow.  Ammonia is transformed by one group into nitrites, and the second group of bacteria changes the nitrites into nitrates.  The plants update the nitrates and other nutrients thereby cleaning the water for the fish.  The water is returned to the fish so that the cycle can continue.

  The end results of such systems is a 20%-30% increase in plant growth, higher density of plants per square foot, reduced water loss by overwatering, and protein from the fish.  These systems can been installed on patios and porches, balconies, and rooftops.  I hope that at the end of this season I will have a better grasp on the dynamics of these systems and the data that will allow further systems to be employed with less waste.  

  Currently I am seeing that the energy use of this system is very little even with a low efficiently pump.  The cost per month is about $2.80.  The grow beds can be up to 4 times the size of the pond that the fish are in if your conditions are intense enough.  Each grow bed currently holds about 20+ plants that will reach full size is 30-50 days.