What is aquaponics?

Some believe the Aztec were first to engage in agricultural use of aquaponics, raising plants on floating islands in fish ponds.

Others refer to ancient Egypt. Either way, it is clear that aquaponics have ancient roots.

What is aquaponics?

Aquaponics is the simultaneous cultivation of plants and aquatic animals in a symbiotic environment where the animal waste by-products that accumulate in the water are used and filtered out by the plants as nutrients, after which the water is recirculated back to the animals. The system consists of two parts; one of them a traditional aquaculture system and traditional hydroponics system, and basically takes the waste by-products generated from aquaculture for use as the nutrient solution for hydroponics. The hydroponics portion of the system in turn acts as the filtration system to maintain water quality for aquaculture portion. Aquaponic systems vary in size from small indoor units to large commercial units. They can use fresh or salt water depending on the type of aquatic animal and vegetation.

Aquaponics, consists of two main parts with the aquaculture part for raising aquatic animals and the hydroponics part for growing plants. Aquatic effluents resulting from uneaten feed or raising animals like fish accumulates in water due to the closed system recirculation of most aquaculture systems. The effluent-rich water becomes toxic to the aquatic animal in high concentrations but these effluents are nutrients essential for plant growth.

Plants are grown with their roots immersed in the nutrient-rich effluent water similar to hydroponic systems. This enables them to utilize the nutrient-rich water and filter out the compounds toxic to the animals. The water coming from the aquaculture part of the system is first allowed to settle in order to remove solid wastes. This also allows time for nitrification of ammonia in the system into nitrates usable by the plants as well as oxygenation of the water. The plants in turn take up the nutrients, reducing or eliminating the water’s toxicity for the aquatic animal. The water, now clean and oxygenated, is returned to the aquatic animal environment and the cycle continues.

Aquaponic systems do not typically discharge or exchange water under normal operation. The system relies on the relationship between the animals and the plants to maintain a stable aquatic environment that experience a minimal of fluctuation in ambient nutrient and oxygen levels. Water is only added to replace water loss from absorption by the plants, evaporation into the air, or the removal of biomass such as settled solid wastes from the system.

The main input to the system other than water is the feed given to the aquatic animals.

Why is bioponics better?

Aquaponics Scientific Article

Growing Duckweed

Growing Duckweed

Growing Duckweed for fish and livestock, and also as a means of removing ammonia and other nutrients from waste water.

Summarized from article published in  Livestock Research for Rural Development
Duckweed – a potential high-protein feed resource for domestic animals and fish
by Leng, Stambolie and Bell.

Fish feed

  • Duckweed has proven to be an ideal feed for tilapia when raising fish aquaponically. Other fish like it too. From our own observations crawfish love it. Even carnivores derive benefit from duckweed. For instance mollies and aquarium fish that prefer live food, will consume the roots of duckweed and the microbes that colonize on the roots.
  • Duckweed may be fed to chickens and livestock. This is particularly important at a time when 30% of industrial corn is used to feed livestock, which is not an ideal food for ruminants. It is an excellent substitute for vegetable protein and supplement for lower-protein feeds like corn. .
  • I feed it to my dog. She loves it! To make it more palatable I add brewers yeast.

Nutrient Profile

  • There could not be a more ideal plant in the entire world than duckweed. Under ideal growing conditions it contains up to 43% protein, 5% lipid and is highly digestible.  What’s more is that it can be grown anywhere there is a high degree of ammonia and phosphorus in the water.
  • Duckweed has a similar nutrition composition to soybeans and is a plant that most closely resembles the protein values of animal meat

Waste water treatment “plant”

  • There is a good deal of evidence that the floating aquatic plant has a great potential to remove contaminants from sewage and may potentially be a nutritional protein supplement for people.

Growing conditions

  • Duckweed species include the most familiar Lemna species are small floating aquatic plants found worldwide. They grow in thick mats that blanket slow moving waters that are rich in nutrients.
  • Duckweeds grow at water temperatures between 6 and 33°C. And it forms a “turion”, sinking to the bottom of a lagoon during colder temperatures, remaining dormant until warmer water restimulates growth.
  • The flat ovoid shape tends to have one or two roots that lengthen when water mineral content is low. For single gut animals, including humans it has no indigestible material, which is in sharp contrast to corn and soybeans which have up to 50% indigestible residues.
  • Duckweed grows best in tropical climates though survives all but deserts and permanently frozen areas. They do not become weeds in water ways because they do not survive in moving water, preferring quiescent conditions.
  • Duckweed grows on water that contains decaying organic matter. It covers the surface, preventing algae from growing on the same organic, mineral rich water.
  • It grows on surfaces that have protection from shade or else is partitioned to prevent excessive movement due to wind and current. Optimal conditions require decaying organics, including ammonia,  phosphate, minerals and trace elements.
  • Under optimal growing conditions, duckweed reproduces at a rate of once every 16-48 hours. By dry weight, this is greater than what can be produced by soy growing on a similar area. As a fish and livestock soy requires energy input for processing. This is not the case with duckweed, which merely needs to be dehydrated. The calcium oxylate that commonly builds up in duckweed that causes a less palatable flavor, can be extracted without electrical energy.  This growth rate is closer to the rate of algae growth, moreso than higher plants, making it optimal for converting waste to nutritious feed.
  • Fresh duckweed contains about 92-94% water.
  • Duckweed is an efficient collector of phosphate and potassium though high levels are not required for fast growth of duckweed. Where P is present in water, duckweed absorption can provide an important source for grazing ruminants when phosphorus feed levels are deficient.  Duckweeds concentrate P up to 9 mg P/g. It also appears as the plant can concentrate trace minerals up to 500,000 times water concentration. Sea salt is a good source for trace minerals and the minerals can be harvested from brackish or salt water growing environments.

Duckweed has been studied for desalinating brackish water.

  • Duckweed grows in brackish water, which often contaminates freshwater aquafers.
  • It can be raised successfully in up to 4000 mg/liter of TDS. Nutrients are absorbed by the duckweed at all surfaces.
  • Ideal pH for growing duckweed is in the range of 6-8, though it tolerates 5-9 ranges. It prefers unionized ammonia which is present in lower alkaline water, closer to the 6-8 range.  Concentrations of free ammonia greater than 100mg NH3/liter are toxic.
  • Duckweed doubles in mass every 24-36 hours. Growth rate of duckweed is controlled by temperature and sunlight moreso than by nutrient concentration. It tends to bleach and die with excessive sun exposure and can sustain rapid growth with even low levels of  phosphorus and nitrogen.
  • Urea is a suitable fertilizer which converts to ammonia in normal conditions. Duckweed is partial to ammonia.

Management systems for duckweed

Duckweed species can withstand  extreme conditions for the most part but management should be focused on maintaining dense growth; (ii) low dissolved oxygen; and (iii) a pH of 6- 7. Dense cover keeps pH low from algal photosynthesis and and it prevents algae CO2 formation from evening respiration and from bacteria respiration of decomposing dead algae.

Duckweed will grow on water containing any waste material. Best sources are from homes, food processing plants, livestock, pig and poultry farms. If using manure and night soil in villages these wastes must be pretreated by storage in anaerobic ponds for several days before cultivating duckweed.

Duckweed as a water treatment “plant”. When using as a treatment system for farms duckweed growing on wastewater should be treated prior to feeding. It will concentrate and store many nutrients, particularly nitrogen, phosphorus, calcium, sodium, potassium, magnesium, carbon and chloride from the wastewater. If heavy metals are also in the water the duckweed may have to be decontaminated prior to feeding to animals.  It grows on water with a nitrogen concentration of 10-30mg NH3/m2.

To grow the plant efficiently in lagoons, it is important to grow the plant evenly across the surface. The density needed to support growth is approximately 1.2kg wet weight/m2 of growing area to as little as .6kg wet weight/m2, for prevention of algae blooms.

Using duckweed as a feed/supplement

Duckweed protein is a more complete  assortment of animal protein than all other vegetable plants and more closely resembles animal protein (Hillman and Culley -1978) than any other plant . With nutrient rich water it will also concentrate carotene and xanthophylls that make it ideal for animals, and it is a rich source of  vitamin A and vitamin B for humans.  For human and some animal consumption some additional measures need to be taken to make the plant more palatable. The high concentration of calcium oxylate crystals makes the flavor less appealing though research is under way at Bioponica to remove the calcium oxylate and prepare the duckweed as a nutritional supplement for infants and malnourished children. Potentially this plant may perform similarly to Spirulina, also used for this purpose and in fact will be more useful as it is easier to raise and grows in turbid water, which tends to inhibit blue green algae growth.

Use of duckweed in fish nutrition

One of the greatest limitations to aquaculture is a source for high protein feed sources with high biological value. Often fish and animals are fed discarded animal waste from meat and fish processing centers. This has proven to be unsatisfactory in livestock feed lots as livestock are fed animal meat despite being herbivores. Mad Cow Disease is a major consequence of this practice. A common problem with feeding animal protein to carnivorous fish is that fish processing discards are commonly used and when fish eat other fish they tend to bio-accumulate toxins consumed in the wild. This is due to the fact that fish may have to eat as much as 10x their body weight per pound of growth. PCB’s and mercury are as such concentrated in farm raised fish. Another problem with manufactured sources of fish food is also seen in livestock feed and that is the practice of feeding chicken manure and chicken urine to fish. While these may be broken down to the same substrates of nitrogen and phosphorus, it is not a natural food for fish and may one day prove to be a problem as is seen with meat fed herbivore livestock, ie Mad Cow Disease. Duckweed is converted very efficiently by herbivore fish including tilapia and carp. It is low in fiber and high in protein which is ideal for fish. It is a

Use of duckweed in pig and poultry production

There is references to multiple sites using fresh, wet duckweed to feed all ruminants, including horses and pigs. Poultry prefer dried. Ducks however have not been researched though it is expected  that duckweed will provide an ideal supplement as a wet meal to any high energy diet. An environmental consultant recently commented to this author that he witnessed a farm feeding duckweed to ducks in a developing country. He commented that the ducks were herded to the ponds daily and returned to their cages. This method of feeding ducks is where the expression arises, “get your ducks in a row.”

While the research on raising domestic animals on duckweed has been scarce it is safe to assume that there are major opportunities. A yield of 10-20 tons of dry atter/ha/year with 40% protein can be reasonably achieved.

Poultry nutrition studies

Dehydrated duckweed has been used to replace alfalfa meal for feeding poultry. Chickens fed 10% dehydrated duckweed had superior weight gain to those fed conventional protein sources.  Layer hens fed on meal from Lemna species of  duckweed at 0%, 25% and 40% have performed very well, however there have been some questions about the performance of chicks, which did not perform as well as adults (Haustein et al 1992b) when fed Lemna.

 Pig nutrition studies.

Little work has been done in this area due to the sheer mass volume that would need to be fed for suitable study, though studies with low protein (25%) has been conducted.  Studies are needed in this area to compare conventional feed of grains to duckweed as the significance of an alternative feed source would be considerable.

Ruminant nutrition

In 1978 a duckweed maize silage diet of 2:1 ratio was fed ruminants and produced a higher than average growth in Holstein heifers vs maize silage: concentrate: grass diet and there were no noticeable differences (Rusoffet al 1978).. The potential benefits of adding wet duckweed to nutritionally deficient dried straw are high particularly if fed to young and lactating ruminants.  With ruminants there is an additional effect that makes it challenging to assess the effects of diet as compared to monogastric livestock. The microbial activity of the rumen alters the availability of nutrients by comparison. Ruminants fed typical diets of mature biomass straws are often deficient of minerals and ammonia which is important for fermentative digestion in the rumen. For maximum feed utilization, they require supplements of protein that often bypass the rumen and are digested in the intestines. The feeding value will require additional assessment as described above with

Special research needs for ruminants

Per the source of the content for this article, additional needs for ruminant research is needed: ”Depending on the nutrient level in the culture medium, duckweeds may be an important source of trace minerals and phosphorus, but if the protein is readily fermentable in the rumen the dietary amino acid supply to the animal will be minimal. In recent studies, Smith and Leng (1993) incubated duckweedmeal in rumen fluid where it was rapidly fermented with the production of ammonia, indicating the extensive degradation of duckweed protein. Treatment with heat, formaldehyde or xylose had little or no effect on the rate of release of ammonia indicating that duckweed protein is difficult to protect from rumen degradation or that a large proportion of the crude protein is as peptide, amino acids and other non-protein-N compounds (unpublished observations). It is likely therefore that duckweed will be initially used as a source of essential microbial nutrients to enhance the efficient fermentative digestion of straw in the rumen. Research is needed to protect the protein before its value as a bypass protein source can be estimated. However, the critical scarcity of protein resources in tropical countries indicates a need for feed technology research to enhance the use of duckweed as a direct proteinsource for ruminants and thus add value to the duckweed (see Leng 1990).”


High protein diet sources are lacking and are the most costly parts of diet for animals in developing countries. Duckweed is a protein source with an amino acid profile that rivals animal protein sources.

Bioponica grows duckweed as a sole source of nourishment when raising fish in the Biogarden. We are presently designing a biogarden system exclusively for growing duckweed. The benefits include waste water treatment and the conversion to value added product. The value added product includes animal feed as well as a biofuel feedstock.

Hydroponics water chemistry

Here is a simple starting point for students and growers interested in aquaponics and hydroponics water chemistry.

is a term used to rather universally to express the intensity of the acid or alkaline conditions of water or soil. In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at 77 F. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline. pH measurements are important in all fields of science and engineering and in plant science are significant by influencing the availability of the Primary and Secondary Nutrients noted above. Included in the Appendices are several charts that illustrate the effects of pH on these nutrients. The width of the bar determines the relative availability of each element with a change in pH.

is a compound of nitrogen (N) and hydrogen (H) with the formula NH3. It is a colorless gas with a characteristic pungent odor. Nitrogen is the mineral element most in demand by plants and the fourth most common element in their composition, being outranked only by carbon (C), hydrogen and oxygen (O). Ammonia is typically formed in soils and water when organic matter such as plant and animal residues containing organic nitrogen compounds are decomposed by bacteria. Ammonia is steadily released into the tank water through the gills and the excrete of fish as product of their metabolism. Higher concentrations of ammonia in the range of 0.5 and 1 ppm can kill fish and plants do not absorb it as well as nitrates.

NO2 is an intermediate product of aerobic nitrification process and is formed when specialized soil and water Nitrosomonas bacteria oxidize and convert ammonia to nitrite. Nitrite levels typically are in the range of .25 to 1.0 ppm in a properly operating system.

NO3 is the final decomposition product of the aerobic nitrification process and is formed when specialized Nitrobacter bacteria oxidize the nitrites to nitrate. Nitrate levels typically are in the range of 2-150 ppm in a properly operating system. During system startup and prior to the nitrififying bacteria being fully established on the BioGarden trough aggregate and plant roots, spikes may occur in the levels of ammonia ( up to 10 ppm) and nitrite (up to 15 ppm ) and nitrate (up to 200 ppm). The nitrification process is affected by pH, temperature, and oxygen level of the water or soil. Optimum pH range for nitrification is 7-8.3; Optimum temperature range is 75-85 F; Optimum dissolved oxygen range of 1.5-3 ppm. When starting a bed for the season, it takes a few weeks to get nitrifying bacteria colonized in the beds. Without the bacteria, ammonia does not convert and so the ammonia builds up and fish can die. A practical way to start a system before introducing fish is to add a cup of pure ammonia (no cleaning ammonia -without detergent or surfactants) to the tanks and let it cycle through the beds for a couple weeks, encouraging nitrifying bacteria to colonize and thereby prepare the rock beds for fish ammonia.

PO4 is released into water and soil by bacteria and fungi during the decomposition of plant and animal organic matter and the solubilization of phosphate containing minerals such as Apatite. Typical hydroponic nutrient solutions require phosphate concentrations of 30-100 ppm and they are adjusted for the particular plant to be grown.

is required for the growth of plants, fish, earth worms and aerobic bacteria such as nitrifiers and decomposers that break down organic matter. For fish and deep water growing conditions, oxygen must be continuously supplied to tanks and troughs. In ebb and flow systems it is needed for the tanks but not the beds, as the beds are continuously replenished with fresh oxygen with each flood and drain, forcing out expired air and sucking in fresh air.

TDS is a measurement of the amount of ions in the water. These are a balance of both positive (cations) and negative (anions). Total Dissolved Solids measures all solids that pass through a 2 micron filter. This includes inorganic ions and organic compounds. Most test meter measures conductivity in millisiemens/cm. Laboratory measurement of TDS is typically more accurate that using meter and conversion as TDS depends upon the ions and organic dissolved in the water but for our operational purposes is an good estimate of actual TDS. I have attached a calculation tool that can be used to more accurately determine TDS based on a fairly complete list of anions and cations that are typically measured by a lab or utilized to formulate hydroponic nutrient solutions. Normal reading range is 800-1500 with 2000 as the upper limit.

Make Compost Tea

Making Compost Tea and Fertilizer Tea

Fertilizer teas have more nutrients than compost teas

We’re doing something different to make plant fertilizers at Bioponica. It is similar to making compost tea but it’s different.  We’re making liquid fertilizer teas.

Compost teas are good for putting plant friendly microbes into solution and multiplying them through aeration and adding simple sugars. Bacteria comsumes the sugars and quickly multiplies. It provides essential elements to improve plant growth.

Worm teas are similar to compost teas, though there’s a bit of a difference with the microbe characteristics. Fungi are more prevalent in compost teas. Bacteria dominate worm teas as they are colonized in the gut of earthworms.

How to make compost teas and worm teas is pretty basic. In a suitable filtration tea bag add a ratio of worm castings. Close bag and introduce to dechlorinated water, preferably rain water or well water. Add sugar, molasses or another natural sweetener to the water and aerate. Within about 24 hours your compost tea is finished and ready to apply to the soil or to your soilless growing system.


Fertilizer Tea

Bioponica developed an easy DIY fertilizer process and inexpensive system making fertilizer teas.

Teas that have greater NPK percentages that compost teas can be considered Fertilizer Teas. We make fertilizer teas to support the Biogarden for deep water culture or for flood and drain techniques within the troughs. This doesn’t eliminate the usefulness of aerated and fermented compost teas and brewed worm teas. On the contrary, they are very compatible.

Bioponica lettuce growing fertilizer tea recipe:

  • 5 lbs blended green kitchen discards (in blender or food processor)
  • or 5 lbs of fresh green yard trimmings (weeds, leaves, grasses).
  • 3 x 2′ Bio-Fertilizer Tea Bag
  • 55 gallon barrel of water (half full)

Soak for 24-36 hours without aeration in the drum or in a 5 gallon Extraction Bucket. Put contents into 55 gallon drum and attache Vortex Aerator and Biofilter. The contents of the bag will remain partially anaerobic. The plant derived extract will quickly convert into a Fertilizer Tea. Good for lettuce or green leafy vegetable grow area of 10 sq ft and will last 1-2 weeks depending on system and plant size.

Vortex Fertilizer Tea Brewer

Operating the Vortex Fertilizer Brewer™

The Bucket Vortex Aerator™ sits upon the Bucket Biofilter™. The inline processing removes water from the drum and passes it through the aerating vortex which spills in to the biological filter.

Place the Vortex Fertilizer Kit™ above the barrel. Connect hoses and turn on the pump.

Tip: If you have access to vermiculture earthworm castings or a decomposed compost pile add 3 lbs of the compost to the 55 gallon barrel after the fertilizer extraction, aeration and filtration has been going for 24 hours. No need to add sugars, as there’s lots of carbon and sugars from the biomass that was used to make the tea.

Leave the Vortex Fertilizer Brewer™ running until the desired amount of carbon and ammonia conversion. Usually 3-4 days. You’ll know when it’s complete, when the turbidity and cloudiness disappears and when the water sweet extract aroma has peaked, carbon is removed, ammonia nitrified and the water becomes mostly odorless.

Happy gardening.

Tomato Fertilizer

Peecycling Urine Fertilizer

Bioponica has found that the use of urine as a plant fertilizer in soilless systems, aka peeponics, is highly effective, as proven by the performance of tomato plants raised in a Biogarden in 2014, entirely from human urine fertilizer.

Most gardeners are familiar with the use of fish urine fertilizer with aquaponics. The logic is straight forward. Urine contains high percentage of ammonia plus phosphorus and trace minerals.  With but a little biofiltration, urine is converted to a more plant available nitrate with NPK values that rival other fertilizers such as chicken feathers and cotton seed meal. In fact, the range of NPK from a liquid urine fertilizer is in the range of 10-18/1-2.5/1.

Food consists of nutrients that are high in protein and various forms of nitrogen, phsophorus and potassium. While the feces contains some of this NPK, most ends up in the urine. So, while the logic of recycing manure is sound for the additional fiber and cellulose that ends up in the compost, it falls significantly short of capturing the most important elements of NPK.

Considering the massive amount of urine excreted by 7 billion people on a daily basis it’s a wonder this source of urine fertilizer has not been capitalized on more widely.

I had the opportunity to visit the non-profit, university based organization ECOSANS on a trip to Sweden a few years ago. Their work was brought to my attention by a UN FAO publication that outlined the steps recommended for handling urine in developing nations agriculture.

Ecosan_closing_the_loop_poster_urine.crop.diversion       Possible_technology_components_for_sustainable_sanitation.urine

Another good use from human urine is the production of struvite. This is a phosphorus compound that can be dried, stored and applied to soil as a self sufficient, sustainable method of sourcing phosphorus. Considering we are near “peak phosphorus” this is no insignificant matter.

Because urine is typically low in minerals, a good means of bringing the NPK values closer to the needs of heavy feeding plants is the addition of wood ash. Wood ash is high in calcium, magnesium and potassium.

Urine and wood ash, two abundant waste products that give us all the NPK the planet could possibly need.



What is bioponics

What is bioponics?