An aquaponic system is made up of a number of chemical processes. But, you don’t need to know formulas or theories to make your system work. By understanding a few chemical processes you can better understand how aquaponics works and how to make your system more productive.
Nutrients in your Aquaponic System
Ammonia in fish excrement is converted to nitrites. These nitrites are converted into nitrates, the nutrients that help the plants grow. Nitrites and nitrates naturally occur as long as there is ammonia in the system. You do not need to add them.
Nitrates are consumed by plants, this completes the process which will remove the ammonia the fish produce (which can be toxic) from the system. This is beneficial to the fish who have clean water and to the plants which have a ready source of plant food.
In a balanced water system, the ammonia and nitrite level would be at 0 ppm. The nitrate level should be kept below 60 ppm for most types of fish. Some fish such as Koi can tolerate a high level, up to 80 ppm, without trouble. The reason the ammonia and nitrite levels are low is because they should be immediately converted and thus removed from the water.
You want to maintain control of your ammonia and nitrite levels, they should not exceed 6 ppm, which can be toxic to fish. Try to keep these levels below 1 ppm for each. Nitrates are acceptable in a range from 40 to 80 ppm. This all depends on the types of fish you choose. Some fish can tolerate higher nitrate levels. Watch your fish to see how they behave at a given range to determine if the level needs to be increased or decreased.
Water Chemistry and Your Aquaponic System
Another measure of a healthy system is the water pH, dissolved oxygen and temperature levels. You can use a standard aquarium testing kit for this purpose. These tests should be conducted regularly starting during the initial system installation.
Sample Water Test Kit
The water test kit can be purchased form an aquarium or pet store. There are a number of different types ranging from simple test strips to liquid test kits. The liquid kits cost more but give more accurate results.
Testing the water pH
You need to monitor your water pH closely. The pH level can tell you how much nutrients are available for the plants in your system and warn you when the system (and the fish) are in danger. An acceptable pH level is between 6.0 and 8.0. The ideal level for an aquaponic system is 7.0.
While you want to maintain the proper pH level, you don’t want to purposefully reduce or increase the pH. It’s better to get fish and plants that are suited for the type of water you have.
While it is possible to change the pH of your system it’s difficult to maintain that level after you manipulate the pH. Eventually it will return to it’s original level and you’ll have to begin the process again. If you find that the pH is not where you want it, don’t throw in the towel, just adjust your strategy and work with your system to make it productive.
Dissolved Oxygen (DO) in Your System
Oxygen is essential to the health of the fish in your system. The oxygen content is effected by the temperature of the water. If the water is cold it can hold more oxygen. If the level of oxygen is low, the fish can suffocate.
The best way to increase oxygen levels is with an aeration system. Add the pump to the aquaponic system and turn it on. The goal would be to have 80 percent saturation but not less than 4 ppm.
The Water Temperature
If you live in an area that experience high fluctuations of temperature you need to keep a careful eye on the temperature of the water. If the temperature drops too low it can impede the nitrification process, the fish will eat less and may die.
It’s important to keep the temperature of the system between 77 and 86 degrees Fahrenheit (25-30 Celsius). This will allow the nitrification bacteria to flourish.
It’s important to achieve balance in your system. Each one of the chemical processes is important to the life and well being of the fish and plants in your aquaponics system. By starting off right (during the cycling stage) you can ensure that you have all of the needed bacteria and elements to establish a healthy aquaponic system.