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Summary of Hydro/Aquatic Technologies plant/fish symbiosis
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Aquaponics is a combination of aquaculture, which is raising fish in a controlled environment, and hydroponics, which is growing plants without soil, providing the nutrients to the plants mixed into the water fed to the plants.

In an aquaponic system, you feed the fish, the fish wastes feed bacteria, the bacteria wastes feed the plants, and the plants clean the water for the fish. Fish waste is mainly ammonia nitrogen, that evil smelling stuff you clean windows with. If you feed the fish too much, and their ammonia laden wastes build up, the fish die. Even if they don't eat the food that you toss in the tank, the natural breakdown of the food will kick up the ammonia level. Certain bacteria eat ammonia, they thrive on it, can't live without it. The most voracious ammonia eating bacteria are called Nitrosomonas bacteria. and give off wastes full of nitrite nitrogen. Another bacteria, Nitrobacter, feeds on nitrites, and excrete nitrates. NitrAtes are 10-100 times less dangerous to the fish. Still, if the levels of nitrates ever manages to get too high, it can still kill the fish.

Nitrates are the form of nitrogen that plants utilize. From the lowest form of blue/green algae to the tallest Redwood tree, they all use nitrates as their nitrogen source. When the plant dies, other forms of bacteria (along with bugs, fish, animals, and humans) feast on the plant. Their wastes start the cycle all over again. An aquaponic system contains all three of the necessary parts of the ammonia/nitrate cycle. They are: fish to produce the ammonia, bacteria to break the ammonia down to nitrates, and plants to feed on the nitrates to create fishfood to start the cycle all over again.

In the simplest aquaponic system, the fish live in a standard fish tank. A pump that sits in the tank with the fish pumps the water and fish wastes up to a series of troughs at the top of the tank. As the water sprays out of the pipes leading from the pump, it picks up oxygen, and flows down the troughs. The troughs contain blocks of rockwool, a sterile growing media similar in appearance to fiberglass. The water and dissolved fish wastes feeds up into the rockwool by capillary action, where bacteria are cultivated. The bacteria do their thing on the ammonia, and feed plants that are also growing on the rockwool cube. The cleansed water then flows down the trough, and pours into the fish area in the tank, completing the cycle. Aquaponics can be integrated into an indoor pond system to create a beautifully landscaped show system.