Do-It-Yourself Aquaponic Greenhouse

Aquaponics combines hydroponics -- growing plants without soil -- and aquaculture -- raising fish, usually as a food source. Combining these systems benefits both. The fish waste provides plants with the nutrients they need, and the plants filter water for the fish. This ecosystem eliminates the need for more expensive chemical nutrient solutions and water filtration devices. A home aquaponic greenhouse can be set up in a 10-by-12-foot space.

There are dozens of hydroponics system designs. Choosing the right system for an aquaponic greenhouse is a key factor for success. Aquaponic systems most commonly use either a constant flow, or ebb and flow, design. Ebb-and-flow hydroponic systems provide better oxygen supplies at the plants’ roots. Constant flow designs aerate and filter the fish water more efficiently. If you plan to maintain fairly high numbers of fish for the size of the tank, opt for the constant flow system and watch the plants for signs of stress. If your goal is optimum growth and production, choose an ebb-and-flow system. In this case, you should install a secondary water filter in the fish tank.

Choose the fish for your aquaponics system carefully. Carp, trout and tilapia are all good choices. They grow and breed quickly, and are easy to cook. If you do not plan to consume the fish, koi make a beautiful ornamental addition to the greenhouse. You should choose fish that are available locally to avoid the cost and complication of importing them from elsewhere. Local fish are also more likely to thrive in your area. You can heat the fish tank to the ideal temperature you want, but if you try to grow warmwater fish in a frigid climate, your system will be less efficient and the energy cost will eliminate some of the savings from growing your own food.

Careful monitoring is essential to the success of any aquaponics greenhouse. There are three factors to monitor: temperature, pH and electrical conductivity (EC). Water temperature is crucial for the survival of the fish and the beneficial bacteria that support plant growth. Levels of pH between 6.5 and 7.0 prevent ammonia spikes in the fish water and provide the optimal environment for plants to absorb nutrients. Electrical conductivity, or EC, levels tell you how much nutrient is available in the water. Ideally, EC levels should be at 2.0 (2,000 microsemens per centimeter), although most plants will grow well at lower levels.

Combination meters are available that will alert you if any of these three factors go above or below optimum levels.