The presence of light, water, and oxygen impact the three organisms living and thriving in an aquaponics system. These organisms include the fish, which serve as a food source for the plants, the plants that purify the water for the fish’s survival, and the nitrifying bacteria responsible for transforming fish waste into nutrients for the plants.
Let’s have a look.
The Significance of Sunlight to Aquaponics
The way light impacts the survival and health of fish, plants, and nitrifying bacteria differs. Here is a breakdown of the effects of light on each of them.
Plants
In order for plants to undergo photosynthesis, light is necessary.
In the presence of light photons, carbon dioxide combines with water to generate glucose and oxygen through a step-by-step process.
Most people choose to position their aquaponics systems outdoors or near a window due to sunlight providing natural light.
Photosynthesis can occur without sunlight as artificial lights can also supply the necessary photons.
Fish
Research has demonstrated that varying light conditions are needed by different fish species.
Certain plants thrive in light conditions for normal, healthy growth, whereas others flourish in dark surroundings.
Fish species generally prefer to have alternating periods of light and darkness, with day length being especially important during the larval phase as it promotes growth.
If your fish are not eating their daily food properly, it could be due to a lack of sufficient light in the aquaponics system, as fish also require light to find their food.
Additionally, the productivity, overall health, and reproduction of fish are influenced by light.
When there is light, the majority of fish will lay eggs. In addition, if fish are deprived of light, they may become inactive, ill, and lose their luster.
It is possible to achieve the above purposes with artificial lighting, therefore fish do not necessarily need sunlight.
When choosing artificial lights, be cautious, as excessive lighting can cause stress to the fish. It is worth noting that certain bulbs also produce heat, which can be detrimental to the fish if there is an excess amount.
Nitrifying Bacteria
Excreta from fish is broken down by nitrifying bacteria, which then convert the nitrogen into nitrates. These nitrates are easily absorbable forms of nitrogen.
These beneficial bacteria do not depend on sunlight or any other form of light.
The growth of these bacteria is indeed affected by blue and ultraviolet light.
Artificial Light for Aquaponics
Artificial light fulfills the same role as sunlight in aquaponics.
The choice you make for your grow lights will depend on personal preference, the type of plants and fish you are growing, as there are numerous options available.
If you choose the incorrect artificial light, it can have negative impacts on your aquaponics, causing stress to the fish, limiting the growth of plants, and resulting in the death of nitrifying bacteria.
Types of Artificial Lights
- Fluorescent Grow Lights: these are relatively inexpensive but are typically only adequate for low-profile plants like leafy greens. Fluorescents are great for seed starting and lighting rectangular beds up to 4′ in length. These grow lights are low-heat lights, so you can put your bulbs close to your plants, making them ideal for low-ceiling growing spaces.
- High-Intensity Discharge (HID) Grow Lights: HIDs are more efficient than fluorescent lights and a much better choice for more extensive and more demanding indoor plants. HID light has an awkward shape and is often used in conjunction with a reflector that directs the light down toward the plants. HID setups are generally configured with interchangeable ballasts, reflectors, and bulbs so you can mix and match the components to fit your style or budget.
- LED Grow Lights: LED lights are the best in the market today. This is because LED manufacturers are getting control over the spectrum of light emitting out of LED fixtures by fine-tuning the range of LEDs on the panel. LED fixtures are more energy efficient compared to other grow lights.
Factors to Consider When Choosing Artificial Lights for Aquaponics
When you are looking for the most appropriate grow lights for your aquaponics, take into account the following aspects:
- Type of light
- Light intensity and distribution
- Upfront and running costs
- Effortless installation and maintenance
- Customization
Type of Light
There are two primary types of lights that are utilized in the artificial lighting of aquaponics. These types include:
- Red light– this light is suitable for a plant’s fruiting stage
- Blue light– plants need blue light for the foliage phase to achieve healthy leaves that are rich in color
- White sunlight– this light is the artificial equivalent of solar light. It’s suitable for the overall growth of plants
- Visible light– also called photosynthetic active radiation (PAR) – is the most suitable light for plant growth. Most plants do well in this kind of light.
If you have a variety of plants in your aquaponics system, opt for visible light.
The best type for your system should be informed by the experimentation and experience of other gardeners.
Light Intensity and Distribution
The measurement of light brightness is known as light intensity and is quantified in lumens.
The number of lumens required for your aquaponics system will depend on its size, as one lumen has the ability to illuminate one square foot.
One option is to purchase a single light that can be strategically positioned, while another option is to buy a series of small bulbs that can be fixed around the aquaponics.
To ensure uniform light distribution, it is crucial to make sure that all parts of your aquaponics system receive sufficient light.
Remember that if certain parts do not receive sufficient light, plants in that area may experience stunted growth or develop leaves that are curled, ultimately resulting in low yields.
Upfront and Running Costs
Before purchasing artificial lights, it is important to carry out market research in order to determine which ones are suitable for your budget.
Although certain lights may have inexpensive initial costs, their operation and upkeep can be expensive.
Effortless Installation and Maintenance
When selecting your preferred grow light, take into consideration the ease of installation, operation, and maintenance.
Customization
It is recommended to choose LED lights that have timers and control knobs, which allow for the adjustment of both the brightness level and the duration for which the lights will be on.
In addition, LED lights possess durability and energy-saving capabilities.
Water
Water is essential for an aquaponics system as it serves as the medium for providing plants and fish with necessary nutrients and oxygen. The presence of high-quality water, rich in nutrients, creates an ideal habitat for bacteria to flourish and nitrify, maintaining a safe environment for the fish.
Monitoring the quality of water in an aquaponics system is crucial as it guarantees the thriving of both fish and plants. To ensure the well-being of your fish and plants, it is vital to closely monitor the water quality parameters such as temperature, pH, water source, and ammonia.
pH
The plants and bacteria in aquaponics are greatly affected by the pH level of the water. Plants thrive in slightly acidic conditions, with a pH range of 6.0 to 6.5, while fish and bacteria prefer slightly alkaline conditions, with a pH range of 6.0 to 8.5. To ensure the optimal pH level for all the organisms in your aquaponics system, you should aim for a pH range of 6.8 to 7.2. This range will enable the bacteria to function properly while providing the necessary nutrients for plant growth.
Regularly monitoring pH levels is essential because any sudden fluctuations can have deadly consequences for fish and plants. If the pH levels in your system become too low, the process of nitrification will decrease or halt altogether, leading to a buildup of toxic ammonia in the fish. Conversely, excessively high pH levels can negatively impact plant growth as well as hinder the development of fruits and flowers.
Temperature
In order to maintain a healthy aquaponics system, it is crucial for an aquaponics grower to consistently maintain the water temperature. This is because the well-being of the fish, plants, and bacteria within the aquaponics system is influenced by the water temperature. Therefore, it is necessary to ensure that the water temperature remains within a safe range for the growth of the fish, plants, and bacteria in the aquaponics system.
The Optimum Temperature Range for Aquaponics
The water temperature ranges of the fish, plants, and bacteria in an aquaponics system are as follows. In general, a compromise temperature range of 68-86 °F or 20-30 °C is recommended.
- Fish
- Tropical Fish: 71-89 °F (22-32°C)
- Cold-Water Fish: 50-64°F (10-18°C)
- Plants
- Most vegetables: 64-86°F (18-30°C)
- Some vegetables like lettuce and cucumber: 46-68°F (8-20°C)
- Other vegetables Like basil: 62-86°F (17-30°C)
- Leafy Greens: 78°F (26°C)
- Bacteria
- Grows in 62-93°F (17-34°C)
- Water Source
Ammonia
Ammonia’s role in an aquaponics system is substantial as it initiates the nitrogen cycle and drives the ecological functioning of the system. Fish excrete waste containing ammonia, which is subsequently converted by bacteria into nitrites and nitrates that are vital for the growth of plants. Through their feces and gills, fish introduce ammonia into the aquaponics system.
The presence of ammonia in aquaponics fish can result in:
- Damage to fish tissues, especially in gills and kidneys.
- Physiological imbalance
- Impaired fish growth.
- Weak resistance to diseases.
- Death
To ensure the ideal environment for the fish, plants, and bacteria in your system, it is crucial to consistently monitor the ammonia level in your aquaponics system.
Oxygen
Fish, plants, and bacteria rely on the water in aquaponics systems to provide them with the necessary nutrients, minerals, and dissolved oxygen they need to carry out their functions. The amount of dissolved oxygen in the water is an important measure of its quality, as it is crucial for the survival of aquatic animals, much like humans need oxygen to breathe. The various organisms in the system, including fish, plants, and bacteria, all require dissolved oxygen for their essential processes.
- Fish for respiration.
- Plants for respiration, health, the strength of their roots, and nutrient uptake.
- Bacteria for nitrification and respiration.
Oxygen for the Fish
Various fish species have varying requirements for dissolved oxygen levels. Most fish species flourish within a range of 4-5 mg/liter of DO and experience optimal growth within this range. When the DO level falls below 4 mg/liter, fish may exhibit behaviors such as swimming near the water’s surface, rapid breathing, and loss of appetite. Warm-water fish species, such as bluegill, catfish, and bass, require approximately 5 mg/liter of DO to maintain their health and promote growth. On the other hand, cold-water fish like trout need around 6.5 mg/liter of DO to ensure their well-being and facilitate growth.
When choosing the best fish for your aquaponics system, it is important to consider that while some fish like tilapia can tolerate lower levels of dissolved oxygen (DO), their growth rates may be affected. Oxygen depletion commonly occurs in the summer due to warm water holding less oxygen compared to cool water. Additionally, high temperatures increase the metabolic rate of fish, thereby requiring more oxygen.
Oxygen for the Plants
Plant roots require oxygen in order to carry out respiration, which is an essential process for the release of energy needed for root growth and nutrient absorption. Oxygen is absorbed by plants through their stems, leaves, and roots during respiration. The majority of plants require high levels of dissolved oxygen, surpassing 3 mg/liter. When roots have access to an ample supply of oxygen, they are able to absorb the necessary nutrients from water and promote optimal plant development.
The impacts of low dissolved oxygen (DO) on plants.
- Root rot.
- Poor ability to absorb suitable amounts of water and nutrients because of the accumulation of toxins.
- The plant root system loses a net amount of nutrients in anaerobic conditions.
- Calcium deficiency in the shoot.
Plants require a greater amount of oxygen during their blooming phase as compared to their vegetative stage due to factors such as temperature, nutrient absorption, and the size of their root system.
Indications of insufficient oxygen supply to the roots of plants:
- Wilting of the plants under warm conditions.
- Browning and dying roots
- Slimy to touch roots.
Oxygen for the Bacteria
In order for the bacteria to perform their tasks effectively, it is necessary for there to be sufficient dissolved oxygen in the water. The bacteria have an ideal range of 4 to 8 mg/liter for dissolved oxygen levels. If the dissolved oxygen level falls below 2 mg/liter, the nitrification process will cease. Nitrification is a biochemical reaction that takes place within the bacteria and involves the conversion of ammonia from fish waste into different forms of nitrogen, such as nitrites and nitrates. Nitrification occurs when the dissolved oxygen level is at 3.0 mg/liter.
How to Increase Dissolved Oxygen in Aquaponics
Increasing dissolved oxygen levels can be easily achieved in small home aquaponics systems with low fish stocking rates. However, commercial aquaponics systems with high fish stocking rates often experience low dissolved oxygen levels. To address this issue, the following steps can be taken to increase DO levels in your aquaponics system:
- Using Air Pump
- Creating turbulence in the water
- Increase Oxygen in the root zone
