System Cycling and Nutrient Uptake in Aquaponics

Nutrients are substances that nourish plants and animals by providing energy for growth and maintaining life. Individual plant and animal species require different nutrients to thrive. In aquaponic systems, fish receive essential nutrients from specially chosen, crafted, and stored food. Companies specialize in producing food for various species such as trout, salmon, catfish, and tilapia. Alternatively, plants in aquaponic systems rely on bacteria to transform fish waste into nutrients. The plants absorb the nutrients out of the water, thereby clarifying the water before it circulates back to the fish tank. 

Cycling your Aquaponic System

Growers can start aquaponic system cycling in two ways - actually starting with fish or without fish. Fish cycling is when producers use fish as the source of system ammonia before establishing efficient bacterial cycling. Fishless cycling requires producers to introduce and grow nitrifying bacteria to mature and efficient colonies for 3-4 weeks before adding fish to the system. The fish are not added to the system until bacterial levels become fully established, and there are no swings in water quality parameters such as ammonia, PH, nitrites, or nitrates occur.  

After establishing a system’s cycling process, fish waste and uneaten fish food become primary sources of ammonia. The remaining food and excrements cycle to a bioreaction area where bacteria transfix the ammonia into nitrites. The nitrites are converted into nitrates, a less toxic form of nitrogen and a usable product that plants can absorb. Nitrates act as a fertilizer; however, nitrogen is not the only nutrient plants need to thrive. Plant nutrients can be divided into two categories - essential and trace elements. Essential plant nutrients include Nitrogen, Phosphorus, and Potassium. These three elements are the most important nutrients for plants and are the main determinants of success. Plants also require trace elements to thrive. Key trace elements include Boron, Copper, Iron, Magnesium, and Zinc. Different types of plants require different amounts of essential nutrients and trace elements to succeed.

Importance of Cycling Your Aquaponic System

Cycling is important in aquaponic systems because it generates the nutrients necessary for plants to thrive, grow and creates a more suitable and clarified environment for the fish. The bacteria work with the fish waste to generate a usable product for the plants. Producers should strive to recognize cycling trends within these systems and maintain water quality parameters accordingly to avoid exceeding species-specific thresholds. High PH typically correlates to high ammonia levels and increased stress levels of the fish. Similarly, elevated ammonia levels can be toxic to fish and cause mortalities. Ammonia becomes toxic at a certain concentration, but that level is different for each fish. For example, Tilapia can handle a higher ammonia level than a salmon or trout.

Producers have numerous options when choosing species of fish and plants to raise together in aquaponic systems. When determining what to grow, producers should consider species temperature constraints, nutrient loads and availability, and the overall feasibility and profitability of the operation. Terrestrial plants are typically included in aquaponic systems to increase profits and system efficiency. Common plants found in aquaponic systems are herbs, tomatoes, lettuce, and peppers. Each type of plant demands different nutrient requirements. For example, basil has a very low nutrient load and does not require any additional supplements. Tomatoes and other fruiting plants have a high nutrient load and often require supplemental nutrients and minerals like iron. Producers primarily use these plants to control nutrient levels in fish tanks and as an extra revenue stream. Individual plant species absorb unique amounts of nutrients, meaning that plant choice directly influences the nutrient load. 

Nutrient Deficiencies

Plants in aquaponic systems can suffer from nutrient deficiencies. Many times, the plant will show physiological and morphological abnormalities. These abnormalities can be diagnosed and sometimes corrected through a balanced nutrient load if caught early enough. Nitrogen deficiency indications include spindly and stunted growth patterns and light green and yellow leaves, while Phosphorus deficiencies slow plant development and create purple undertones to the bottom of particular leaves. Potassium deficiency indications include browning and yellowing of leaves and leaf decay. Trace element deficiencies also trigger adverse effects in plants such as stunted growth, decreased chlorophyll production, discolored leaves, and brittle consistency.

How FarmHub Software Can Help

Notebooks

Aquaponic AI software can simplify the complex process of nutrient cycling, species choice, and nutrient deficiencies for farmers. Aquaponic AI offers notebooks designed to track water quality parameters that farmers can utilize for data input, secure storage, and auto-generating graphs based on provided data. These notebooks and trends paint a clear picture of what is happening within the systems.

Alerts & Standard Operating Procedures

The alerts, task chart, and calendar will remind farmers of what should be accomplished that day and help producers stay on track. Aquaponic AI offers a system cycling chart that graphs where a system is in the cycling process. The chart follows producer actions and chemical levels such as adding an ammonia source, bacterial conversions, and when the system is properly functioning at peak bacterial performance.

Nutrient Availability Chart

Watching for nutrient availability is one of the most important things to your plants as you’re growing. Farmers will want to make sure that pH and other water quality parameters are within a range that’s suitable for plants to grow and flourish. We’ve developed a Nutrient Availability Chart within our dashboard in order to help farmers see exactly where nutrients are and how much they’re available to the plants.

In this chart you can learn the values for the different nutrients (both macro and micronutrients) and how they are change depending on the pH level. In general Aquaponic practitioners run a system anywhere between a pH reading of 6 and 8.

If you’re looking to run your system between pH 6.8 and 7.2 you can see all the available nutrients for your plants.** If a system is struggling to keep pH low and seeing lots of deficiencies, then a farmer can troubleshoot and see which nutrients are lacking at those higher pH levels. **Such insights and visualization of a system can help when growers are trying to understand why they are having a nutrient deficiency.

Ammonia Toxicity Chart

An ammonia toxicity chart on the dashboard helps inform farmers of where systems stand on a toxicity level. Finally, the research section provides a crop profile for species common in aquaponic systems. This profile includes information on factors determining success and helps producers match plant nutrient requirements to fish parameters. The disease and nutrient deficiency section, also located under the research tab, highlights issues plants struggle with.  

Streamline Your Operations

The cycling process and starting out your aquaponic system is a fun and exciting time as you watch nature do it’s work. Whether you decide to start the cycling process using fish or fishless methods, proper nutrient cycling is paramount to the success of fish and plants in aquaponic systems. As you get started with your system, let us help simplify this complex process by tracking all elements that factor into cycling and providing insights and visualization of the process.