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Safety at work
Safety is important for both the human operator and the system itself. The most dangerous aspect of aquaponics is the proximity of electricity and water, so proper precautions should be taken. Food safety is important to ensure that no pathogens are transferred to human food. Finally, it is important to take precautions against introducing pathogens to the system from humans. Electrical safety Always use a residual-current device (RCD). This is a type of circuit breaker that will cut the power to the system if electricity grounds into the water.
· Food and Agriculture Organization of the United NationsRoutine management practices
Below are daily, weekly and monthly activities to perform to ensure that the aquaponic unit is running well. These lists should be made into checklists and recorded. That way, multiple operators always know exactly what to do, and checklists prevent carelessness that can occur with routine activities. These lists are not meant to be exhaustive, but merely a guideline based on the systems described here in this publication and as a review of the management activities.
· Food and Agriculture Organization of the United NationsProduct quality
In cultured fish, particularly freshwater species, there is often the risk of off-flavour. In general, this reduction in flesh quality is due to the presence of specific compounds, the most common of which are geosmin and 2-methylisoborneol. These secondary metabolites, which accumulate in the lipid tissue of fish, are produced by the blue- green algae (cyanobacteria) or by the bacteria of the genus Streptomyces, actinomycetes and myxobacteria. Geosmin gives a clear muddy flavour, while 2-methylisoborneol gives a mildewed taste that can severely affect consumer acceptance and disrupt the marketability of the product.
· Food and Agriculture Organization of the United NationsPlanting design
The layout of the grow beds helps to maximize plant production in the available space. Before planting, choose wisely which plants will be grown, bearing in mind the space needed for each plant and what the appropriate growing season is. A good practice for all garden design is to plan the layout of the grow beds on paper in order to have a better understanding of how everything will look. Important considerations are: plant diversity, companion plants and physical compatibility, nutrient demands, market demands, and ease of access.
· Food and Agriculture Organization of the United NationsPlant selection
To date, more than 150 different vegetables, herbs, flowers and small trees have been grown successfully in aquaponic systems, including research, domestic and commercial units. Appendix 1 provides a technical summary of, and detailed growing instructions for, the 12 most popular herbs and vegetables. In general, leafy green plants do extremely well in aquaponics along with some of the most popular fruiting vegetables, including tomatoes, cucumbers and peppers. Fruiting vegetables have higher nutrient demands and are more appropriate for established systems with adequate fish stocks.
· Food and Agriculture Organization of the United NationsPlant health, pest and disease control
Plant health has a broad meaning that goes far beyond just the absence of illnesses; it is the overall status of well-being that allows a plant to achieve its full productive potential. Plant health, including disease prevention and pest deterrence and removal, is an extremely important aspect of aquaponic food production (Figure 6.8). Although the most important advances in plant health have been achieved through the management of pathogens and pests, optimal nutrition, intelligent planting techniques and proper environmental management are also fundamental to secure healthy plants.
· Food and Agriculture Organization of the United NationsOther major components of water quality: algae and parasites
Photosynthetic activity of algae Photosynthetic growth and activity by algae in aquaponic units affect the water quality parameters of pH, DO, and nitrogen levels. Algae are a class of photosynthetic organisms that are similar to plants, and they will readily grow in any body of water that is rich in nutrients and exposed to sunlight. Some algae are microscopic, single-celled organisms called phytoplankton, which can colour the water green (Figure 3.
· Food and Agriculture Organization of the United NationsNutrient film technique (nft)
The NFT is a hydroponic method using horizontal pipes each with a shallow stream of nutrient-rich aquaponic water flowing through it (Figure 4.60). Plants are placed within holes in the top of the pipes, and are able to use this thin film of nutrient-rich water. Both the NFT and DWC are popular methods for commercial operations as both are financially more viable than media bed units when scaled up (Figure 4.
· Food and Agriculture Organization of the United NationsNitrifying bacteria and the biofilter
Chapter 2 discussed the vital role of nitrifying bacteria in regard to the overall aquaponic process. The nitrifying bacteria convert the fish waste, which enters the system mainly as ammonia, into nitrate, which is fertilizer for the plants (Figure 5.1). This is a two- step process, and two separate groups of nitrifying bacteria are involved. The first step is converting ammonia to nitrite, which is done by the ammonia-oxidizing bacteria (AOB).
· Food and Agriculture Organization of the United NationsNew aquaponic systems and initial management
Building and preparing the unit Detailed step-by-step building instructions are provided in Appendix 8. Once the unit is complete, it is time to prepare the system for routine function. Although aquaponic unit management does not require excessive time and effort, it is important to remember that a well-functioning system requires a minimum of 10-20 minutes of maintenance every day. Before stocking a new system with fish and planting the vegetables, it is crucial to ensure that all of the equipment is working properly.
· Food and Agriculture Organization of the United Nations