Backyard and Hobby Systems

Aquaponics is a great hobby and an even better way to produce food in your own backyard. A small backyard aquaponic system can produce enough food to feed your family.

System Design:

Backyard aquaponic systems use the following equipment.

• One pump only - for energy efficiency

• medium bed hydroponic components

• Tubing for water delivery to and from the grow beds

• Thermostatically controlled aquatic heater to maintain the required water temperature in the system water

• The use of clay or gravel hydroponic grow bed medium

• The necessary kits to test the pH of the water on a regular basis

The Pump

A properly designed and constructed system will only require one pump to operate efficiently.  When you locate the outlet from your grow bed higher than your fish tank, only one pump is required to move the water from the fish tank to the grow bed and then it is returned to the fish tank through tubing by gravity flow.

Grow Bed Hydroponic Component

Gravel used as a grow bed medium is the most efficient hydroponic component for a backyard or hobby system.

This is due to several reasons:

• good plant support

• higher plant growth & yield

• better water buffering

• additionally the gravel will act as both a bio and solids filter.

For systems not using gravel in the grow beds, more water filtering components are required which raises the cost of system construction.

Constant Flow or Ebb & Flow Water Delivery

Ebb & Flow system of water delivery to the gravel beds is done because it enhances root zone oxygen and saves energy which are valid reasons.  Constant flow can be used  and has been found to actually improve water quality in terms of ammonia levels.  Better nitration of the water leads to increased plant growth rates and yields.

Constant flows systems do produce lower dissolved oxygen at the root zone requiring some form of aeration in the fish tank.  Additionally, the constant flow system will require a simple solids removal device to help to prevent the solids from competing for oxygen.  You should always remove as many solids as possible from the aquaponic system to prevent clogging of the grow bed medium which can lead to toxic conditions which can kill both fish and plants.

Aquatic Water Heating

Aquaponic systems work much better if a constant water temperature is maintained as beneficial bacterial species that convert ammonia to nitrate have a temperature range between 70^o F and 86^o F at which they operate at maximum efficiency.  At temperatures below 64.4^o F, a bio-filter's efficiency is lost and ammonia spikes can occur.  You should always strive to try maintain a water temperatures at or above 64.4^o F in the winter though it should be at least a minimum of 70^o F for certain species of fish to survive, Tilapia in particular.

There are many methods to accomplish this, however electrical aquatic emersion heaters such as are used in aquariums can do the trick on a small scale. However, if you want to go a step further, use of a simple solar water heater for aquaponic systems can be rigged very inexpensively.  Plans for such homemade solar system can be found if you will CLICK HERE.   Additionally the use of insulation around the fish tanks, gravel beds and water tubing will help to retain heat.

Correct Grow Bed medium

Grow Bed medium comes in many shapes and forms and few people state which medium is good or bad because each has it good and bad points.  Red Scoria for example is a very dusty medium and should be rinsed thoroughly to eliminate every trace of red in the water.  If this is not done and done properly it will slowly contaminate the entire system in a light layer of red dust that can cause any number of problems from harboring ammonia to clogging the medium with a reddish layer of red mud.

Scoria also sports very sharp edges making it difficult on the hands and plant stems. However, the owner could see no problem with this, and was happy to feed the plants and fish to his family. Some gravels may contain toxic chemicals and compounds, like heavy metals and minerals such as calcium which is also another item which can clog pipes and medium by encrusting it.  Choose carefully and always make sure your grow bed medium has never come into contact with herbicides, insecticides, petroleum or any other chemicals of any kind.

One medium that is a good choice is washed river gravel has nice with its well rounded edges that are easy on both hands and plant stems.  Get it at a size of about 1/3 inch to 3/4 inch in diameter. Gravel that is too small in diameter can clog very easily and will retard or halt water movement all together.

Water pH Testing A Must

Conductivity, pH and temperature are the 3 main parameters that need to be tested in aquaponic systems. 

pH - fish and plants live at different optimal pH levels.

• For fish, this around a pH of 6.5 to 8.0

• For plants, this around a pH of 4.5 to 6.5.

Hence a compromise of pH must be made to accommodate the requirements of the fish and plants.  The optimum pH is around 6.7 to 6.9. This will protect the fish against ammonia toxicity and allows the plants to uptake the nutrients they require for growth.  pH may be tested with simple pH kits and electronic pH meters obtainable from aquarium stores at various prices according to how extravagant you wish to be.

Conductivity - is a measurement of the amount of dissolved nutrients in the water.

• The higher the conductivity is, the more nutrients there are.

• An acceptable amount of nutrient availability in the water is an EC of around 2.0 (2,000 microsemens/cm).