Aquaponics Information for Beginners:
The following is all about Aquaponics System.
Introduction to Aquaponics System
Aquaponics is a system or science in which the waste produced by aquatic creatures or farmed fish supplies nutrients for plants growth hydroponically which in turn purifies the water; this is an automatic recirculating system that does not require much monitoring is called Aquaponics or Aquaculture. This is a sustainable method of producing healthy, fresh, and cost-effective foods such as protein and vegetables to the local urban community. Aquaponics is an integration of fish farming and plant farming in a soil-less culture that uses inert growing media to grow agricultural crops and aquatic creatures together. Aquaponics comes in many designs serving a different purpose, but all systems share the basic purpose. Fish that are grown by feeding fish food will defecate and urinate which settle downs at the bottom of the tank. Fish waste over a period of time becomes toxic to the fish due to the over-accumulation of ammonia in the water. The water needs to be filtered for the fish to survive. Beneficial bacteria exist on every moist surface convert the ammonia in the water into nitrites and then into nitrates. Nitrates provide organic food for the growing plants and which is relatively harmless to the fish. The water containing nitrates is pumped into the beds where plants are grown hydroponically. The roots of the plant absorb the nitrates in the water thereby purifying the water and the purified water is sent back into the fish tank. This is an ongoing cycle process which needs minimum care that helps fish and plants to grow.
Understanding Biological Components of Aquaponics System
The Nitrogen-fixation process is the most important biological process in aquaponics. The most important inorganic nutrient for any plant to grow is Nitrogen. In the nitrification process, ammonia is broken down by fungi and useful bacteria by converting them into nitrate compounds and nitrate compounds. This natural process of converting fish excreta into nitrates by the beneficial bacteria, which in turn becomes feed for plants, and the plants acting as bio-filters purifying the water in the aquaponics system. The entire arrangement of aquaponics is totally dependent on the bacteria. In the event that this is absent the excreta high concentrations in the water will slaughter the fish. In order to keep the ammonia levels in the water to zero, a healthy bacterial colony is very important. These bacterial colonies will prosper on any materials such as fish tank walls, pipe walls inside, and even on plant roots. The more the surface area the more ammonia conversion rate by these bacteria. The bacterial colonies also maintain the pH levels of water. The ideal pH range is 6 to 7 as this is good for both plants and fish. Water temperature has to be maintained throughout the season. Bacteria growth is based on water temperature, the growth of bacteria can come down to 50% if the water temperature is below 10° C. The ideal water temperature to be maintained for bacterial growth is 17° to 35° C. Oxygen levels in the water also is an important factor in aquaponics. This helps in proper bacterial growth on the surface which will lead to healthy nitrification process. The optimum oxygen level in the water to be maintained is 4 to 8 milligrams per liter. When oxygen levels are not properly maintained then it will lead to unusable nitrogen called as de-nitrification. When starting aquaponics, ensure the bacteria is colonized on materials having high surface. Since this bacterium is photosensitive, cover the fish tank with UV protective material till the bacteria colonies are fully formed in the initial three to four days. Ammonia and nitrite levels in the water must be less than 3 milligrams per liter and nitrate content must be less than 400 milligrams per liter.
Designing and Building of an Aquaponics
Environmental and biological factors must be taken into consideration while designing an aquaponics unit, which will have an impact on aquaponics ecosystem. Location of an aquaponics unit plays a major role, when it is placed in an open place such as rooftop or backyard without covering then factors such as sunlight, wind, rain, and others must be taken into consideration. For best aquaponics production with low maintenance, it is recommended to have it in a greenhouse or net house. There are three types of aquaponic system – Deep water culture. Flood and drain, and Nutrient film.
Common components that are used to build an aquaponic system are:
- Fish tank – To grow fish.
- Grow-beds – Plants are grown.
- Water Pump – To move water from lowest part of the fish tank to grow beds.
- Air Pump–For oxygenation of the water in the fish tank.
- Growing Medium – Used in grow beds for plant root support and biological filtration.
- Water Pipes and Tubes – Used for water to flow from fish tank to grow beds and back to fish tank.
- Grow-beds – Where plants are grown.
Deep Water Culture: It is also called a floating raft. In this design, plants are grown in Styrofoam sheets which float on the water surface of the grow beds. This is the simplest way to design. Water from the fish tank flows into grow-beds continually through pumping and overflows back into the fish tank continually. Water passing from the fish tank to grow-beds must be filtered either mechanically or biological filter to remove particulate matter which will clog the plant roots. Water in the grow-beds must be aerated by inserting air pump which helps to prevent root rot.
Flood and Drain: In this system, plants are grown in a grow-bed filled with substrates or growing medium. The purpose of the substrates is for plant root system support along with it, it acts as a water filter. When water from the fish tank starts filling in the grow-bed, it brings nutrients into the plant root zone. Air is drawn into the plant root zone when the water begins to drain while returning back to the fish tank. This mechanism of flooding the grow-beds and draining the water back into the fish tank is a continuous process which can be controlled mechanically by running the water pump on a timer, or by building auto siphon which acts as an automatic draining device in the grow-bed.
In flood and drain system, we require a big water tank for growing fish, a grow-bed, growing medium or substrates, water pump, air pump, sump tank, and PVC pipes. Place the fish tank wherein the water level is higher than the grow-beds. Make a drain outlet at the bottom of the fish tank that will continuously send the water from the bottom bed of fish tank where the fish excreta gets settles down. The grow beds are placed near the fish tank a little below the drain outlet, water flows from the fish tank into the grow-beds. The substrate acts as biological and mechanical filters. As the water gets filled up in the grow-beds, the automatic siphon drains the water from the grow-beds into the sump tank that is placed lower than the grow-bed. The collected filtered water from the sump tank is pumped back into the fish tank. This is a continuous ongoing process which lets the water level in the fish tank to remain constant at all times. The water that is collected in the sump tank is free from particles hence the chances of water pump or connecting pipes to the fish tank won’t get clogged.
Nutrient Film Technique (NFT): This is a fairly simple design where most of the home hydroponic growers implement at the beginning stage. This system works well in growing plants that are small and quick to grow such as lettuce, herbs, and baby greens. The designs vary depending on the availability of open space and the number of pipes that can be placed. Irrespective of the different NFT designs, they all follow the same basic characteristic of shallow flowing of nutrient water downward through the piping. PVC pipes are drilled with equal size hole at a regular distance along the pipes. Net cups either with substrates or rock-wool along with plant saplings are placed in each hole in the pipe. The bare root from the net cups come in contact with the flowing water and absorbs the nutrients from it. The major drawback of this system is the water must be continuously flowing without any break as this will lead to wilting and the plants die over a time.
This system requires a fish tank for the fishes to grow, a submersible water pump, filters to particulate solid matter, tubing for water distribution, and PVC pipes for plants to grow. The submersible water pump pushes the water from the bottom of the fish tank into the filters. Here the filter collects all the solid matter and allows only the nutrient-rich water into the PVC pipes. The plants growing in the pipes will receive nutrients from the water that is flowing into the plant root zone thereby filtering the water from nitrates. The purified water thus flows down from the PVC pipes into the fish tank thereby creating a continuous cycle.
Nutrient Requirement in Aquaponics
Nutrients play an important role in aquaponics. It is observed in much commercial aquaponic farming, the production of vegetable is more convenient and profitable than the fish. Maybe, it is because of the quick growth rate of plants compared to fish growth. However, by growing valuable fish can make a change to earn more. The tiny root hairs in the root zone help in absorbing the nutrients. In aquaponics, the roots absorbing nutrients is phenomenal and stimulates the plant growth by maximum delivery. For proper growth of plants, they require both macronutrients and micronutrients for healthy growing and reproduction. Unlike, in soil farming, the plants are completely dependent on fish waste for nutrients. Although fish waste contains all these macro as well as micronutrients some nutrients may be inadequate for the certain type of plant varieties. This may affect the plant growth when nutrient deficiencies occur. In such cases, the grower must identify which nutrient elements are lacking in the system and accordingly must be adjusted by adding minerals or supplemental fertilizers in the water. Usually, the elements such as potassium, calcium, and iron quantities are found to be inadequate in aquaponics. The common way to find out the deficiency of nutrients is by testing water pH levels. The water pH levels must be maintained between 6 to 7 ranges. Fish in the fish tank must be provided with complete and balanced fish food. Even at times, the feed rate ratio of fish feed to balance the plant feed may become deficient in certain nutrients.
Plants in Aquaponics
Researchers who are working extensively in hydroponics have said that about 150 various varieties of vegetables, herbs, flowers plants have grown successfully in aquaponic systems. Planting of plants must be done with a thorough understanding of the nutrient requirement for each plant types. Leafy vegetables, herbs, and grow very well giving a high yield. There are some fruit vegetables that need more nutrients for their healthy growth. Depending on the plants you want to grow, the grower has to choose the aquaponic design and the stock of fish. Care must be taken while choosing root crops, as some root crops may not grow well in this system. Root crops are usually sensitive to water content around the root zone and need special attention. Choose the right design such as wick beds or deep growing medium beds for proper growth.
- Herbs and Leafy Vegetables: Lettuce, Basil, Mint, Chard, Salad Rocket, Spinach, Parsley, Coriander, Watercress, Stevia, Pak Choi, and Chives require fewer nutrients.
- Legumes: Peas and Beans require fewer nutrients.
- Fruit Vegetables: Tomato, Cucumbers, Zucchini, Eggplants, and Peppers require low nutrients; Kale, Broccoli, Kohlrabi, and Cauliflower require high nutrients.
- Fruits: Strawberries, Melons, and Squashrequire moderate to high nutrients
- Root Plants: Radish requires fewer nutrients; Onions, Taro, Beets, and Carrots require moderate to high nutrients.
Fish in Aquaponics
Growing fish in aquaponics, a grower must have little knowledge about how fish breathe food digesting and fish excreta. Along with this, they should have knowledge about fish feed conversion ratio which is important in aquaponics. A grower must acquire more knowledge when it comes to conversion of feed to body mass, the life cycle of fish relating to reproduction, breeding, and fish stock maintenance. Fish are sensitive to water temperature as they are cold-blooded animals. Maintain water temperature depending upon the types of fish. Tropical fish require 22° to 32° C and cold water fish require 10° to 18° C. Fish like mammals have sensory organs. They taste, smell, touch, hear, and detect electrical fields; hence handling of fish must be taken with proper gentle care.
- Food Fish: Catfish, Tilapia, Bass, Blue Gill,
- Ornamental Fish: Koi and Goldfish
- Exotic Fish: Barramundi, Jade Perch, Silver Perch, Murray Cod.
Fish requires protein for gaining body mass along with carbohydrates, fats, vitamins, and minerals for their healthy growth. Fish feed pellets are available in local fisheries which will be a proper complete diet food. Depending on the feeding habits of fishes, choose pellets that float or sink for their feeding. Observe the feeding habits of fish; usually fish consumes feed within 15 minutes. Excess fish feed that remains in water must be removed as it may lead to increase in toxic levels in less time. It is recommended to avoid overfeeding.
Best Management Practices and Troubleshooting in Aquaponics
Balance is the keyword for best management practice in Aquaponics. Fish must supply balanced nutrients to the plants; plants need to filter the water giving balanced purified water back to the fish. Balance is the tricky part in aquaponics growing and achieving it leads to healthy overall growth with maximum production. Fish must be fed two to three times in a day but without overfeeding. Usually, fish eat feed about 1.5 to 2% their body mass per day. Feed rate ratio means the amount of feed fed to the fish for plants growing in a square meter area. The optimum feeding rate ratio depends on many factors such as plant varieties, types of fish, and types of aquaponic system. Below table gives a general information about feed rate ratio in general for aquaponic farming.
|Plants||Fish Feed per sq. m per day||No. of plants per sq. m|
|Leafy Greens||40 to 50 grams||20 to 25|
|Fruit Vegetables||50 to 80 grams||4 to 8|
|Fish Density||18 to 24 Kg fish per 1000 liters of water|
Maintenance Activities of Aquaponics:
- Visual inspection of the water pump, air pump, and free flow of water. Check water levels in sump and fish tank and the automatic siphons functioning properly.
- Fish Feed: Feed fish timely and with the right quantity of feed. Remove the leftover feed at the earliest.
- Check Plants: For wilting, pests, and diseases. Treat them appropriately.
- Check Fish: Remove dead fish, Observe fish behavior, appearance, and sick fish.
- Check Water: For water leakage, water levels in tanks, temperature, and pH levels.
- Miscellaneous: Clean pipes that are clogged, rinse clarifier and filters that are accumulated with solids. Collect ripe fruits and fully grown leafy plants.
- Check water quality for KH and pH levels. And adjust accordingly.
- Check plants having growth deficiency and add fertilizers as necessary.
- Clear fish solids accumulated at the fish tank bottom.
- Planting and harvesting of both vegetable and fish as required.
- Check plant root growth and ensure they are not obstructing water flow.
- Check for any root growth inside siphon pipes by running a sharp knife along the inside walls.
- Clean the all the pipes and tubes with a bottlebrush.
- If required, stock new fish.
- Check fish thoroughly for any disease and treat as necessary.
Overall check for the human and system safety. Avoid spoiled or expired fish feed. Necessary precaution measures must be undertaken for electrical safety.
Conclusion of Aquaponics
A good aquaponics performs well on the health of bacteria, plants, and fish forming a complete aquaponic ecosystem. A little knowledge on plant and fish growing conditions will be remarkable for good production and for commercial growers; they need to use practical experience along with good subject knowledge. In a little period of time with test and trial experiences, one can master aquaponics. Most of the aquaponics knowledge comes through practical experience. When the population is increasing worldwide at a tremendous rate, food scarcity is also increasing. Much of the deforestation and depletion in soil nutrients is increasing. Aquaponics solves most of these issues both vegetables and protein requirement while leaving no carbon residue. Harvest products of the aquaponic system are free from pesticides, herbicides, and chemical fertilizers.