Aquaponics Reference

This is a "research paper" I wrote.

Aquaponics: An Organic Balance.

"Aquaponics is the cultivation of fish and plants together in a constructed, re-circulating ecosystem utilizing natural bacterial cycles to convert fish wastes to plant nutrient”—to clean the water for the fish. (“What is Aquaponics” by Sylvia Bernstein, president of TheAquaponicSource, and contributions from community members on aquaponicscommunity.com--now community.theaquaponicsource.com)

Aquaponics is the integration of aquaculture, the growing of aquatic animals (mostly fish), and hydroponics, the soilless growing of plants through specific nutrients and water. Aquaponics works by utilizing the nitrogen cycle, the conversion of ammonuim and ammonia, in equilibrium with each other,   NH₄⁺ and NH3 respectively, to nitrate, NO₃^- . The conversion works by nitrifying bacteria, nitrosomonas and nitrobacter, converting Ammonium, produced by fish through their gills, into nitrite, and nitrite into nitrate. The plants use this nitrate as fertilizer, as well as, micronutrients found in the fish waste to clean the water to the fish; if any of these gets to high, stress or death may occur, a 1/3 water change will then be required. This is a recirculating method, aquaponics, though efficient and organic, requires significant energy. Solid matter excreted from the fish needs further processing in order to keep the macronutrients and micronutrients in the system. Composting red worms helps the degradation process of organic matter, like in soil, thus adding the nutrients back into the system without supplemental care. Aquaponics is completely organic; the use of chemicals would harm the fish and bacteria needed for a balanced ecosystem.

There are 4 basic types of aquaponic grow-bed design: (1) media based, these are found to have higher filtration capacities by many formal and informal studies; (2) deep-water-culture beds, they are separate beds where Styrofoam is used to keep plants stable, solids removal is necessary and shrimp can do this well; (3) NFT (nutrient film technique), a process of water going through pipes or gutters to provide nutrients for the plants, though common in hydroponic farms NFT has been deemed by many to be ineffective alone in aquaponics (read about Dr. Lennerd's foray into NFT Aquaponics and its success) ; and four, passive, these are simple floatation devices, often Styrofoam that sit atop the fish tank, plant roots collect solids and die unless a useful polyculture is created. The Mixed systems have at least two of the systems described here integrated; the systems we will be using are mixed. (NFT and Media) The key word for NFT is that alone it may be ineffective, but given adequate settings is more space efficient than media or deep-water-culture. A combination of media and NFT is the zip-grow tower, the zip-grow tower is filled with media and water flows through it, it’s hung for greater efficiency. Our systems need to be space efficient, so the filtration of media is combined with the space-efficiency of NFT thus insuring a bountiful harvest. “Most AP designs are expansive. I wanted to look at working in a small footprint. Gravel beds are very versatile filters, and as time has shown, simple and effective NFT / raft beds have shown to be highly productive, often more so than gravel beds according to some authors.” (Kobus Jooste of aquaponic gardening)*

However one “hot topic” on the minds of all who do aquaponics, where do the systems get Ammonium from? Most aquaponic systems use fish feed but, a plethora of options are useful for omnivorous fish species, like tilapia. Carey Ma*: “I started out many years ago raising Fancy Guppies and Siamese Fighting fish and supplemented their flake diet with mosquito larva I raised in a tank on the side. Live food always seems to perk them up so I have continued this practice to this day. Today I have a 10 x 20 “bug shed” attached to one of the greenhouses, raising crickets, red wigglers, meal worms, mosquito larva, grubs and black solider fly larva for my chickens and fish as both live and pellet(ed) feed.” (emphasis mine) *these are well respected people in the aquaponics community (community.theaquaponicsource.com formerly aquaponicscommunity.com): Carey has been using aquaponics since the 1970’s and Kobus is in academia. Obviously this is a big operation, so why do many people take great care in what their fish eat? Pellet fish-feed is expensive on both the wallet and environment. In addition the ultimate goal for the average aquaponic gardener is sustainability or at least highly efficient integrated systems. Pellet feed for tilapia is derived from fishmeal and binding starches, much effort has been given in making a suitable aquaculture feeds for many fish. Other options include duckweed, possibly derived from extra toxic ammonia, black soldier fly larvae (BSFL), which are avid composters, and scraps from the garden or kitchen. Duckweed: there has been an explosion in duckweed production, for feeding fish, since the explosion in integrated systems as a whole. “It is winter now thus I am expecting that warming temperatures may push the ammonia content of the water up to the critical 2 mg/L TAN that I am looking for as an upper carrying capacity indicator, but presently it is rock steady at 0.25 or lower, suggesting that just about all the Ammonia produced by the 55 fish in the system is absorbed daily.” (Kobus Jooste) The quote refers to a system comprised of fish and duckweed. Though not aquaponics, it can be integrated with aquaponics. BSFL are also important to feeding fish as they are high in proteins and lipids. Though not a nutrition source on their own on account of their lipid content; BSFL are useful for encouraging quick growth.

Fish and plants require special care if a successful crop is to be created; protection from disease, pests, lack of nutrition, overabundance of needed minerals, and “weather conditions” needs to be a top priority of any grower, especially a self-contained system like a greenhouse. Dealing with fish disease is one of the most important parts of aquaculture. In aquaculture, high densities of fish cause disease to spread like wildfire. The dense stocking of fish also causes stress and the result is varied from stunted growth, due to changed eating habits, to death. This is also due to fighting; fighting can ruin a crop of lucrative fish. Dense stockings also produce large amounts of ammonia and organic matter, the fish do not respond well to swimming in their own waste. When ammonia, nitrite, or nitrate levels are to high the fish die, due to poisoning. Therefore in an integrated system balance should be the first precaution. If the problem persists check to see if overcrowding is an issue. The best advice for that is to eat more fish. If fish seem stressed check the water quality.

The most common pest, for plants, is aphids. Aphids are used by ants as a nutrition source, farming, in such the same way as cows are for humans. Aphids cling to the stems of the plant, or graze, and make their way to the upper part of the plant, this stunts growth. To contain aphids a grower must: look for signs of stress on plants, look for the aphids themselves, and take action. Actions may include spraying them with a soap type product, destroying the membrane that allows aphids to live. Picking aphids of the plant and killing them in any way you see fit. As well as, dunking a plant into the fish tank, though try not to destroy the root system.

Mineral deficiencies are when plants don’t have the required nutrition to function. Common deficiencies are, iron, Fe, magnesium, Mg, Potassium, K, Calcium, Ca, and Phosphorus, P.

	Dryness	Wilting	Discoloration	Spots
Fe			Yellowing
Ca		Yes
Mg			Gray Sheen
P				Yes
K	Mature Leaves

There are many signs yet some are harder to recognize than others, so a good knowledge of plants is recommended but not needed.

An overabundance of minerals can have harmful effects on plants in soil, but the fish will be hurt first in an aquaponics system. Overabundances can occur when hydroponic nutrients are added to the system, the biofilter is damaged, or more likely the grower has fed the fish far too much of one thing, or all things. When you, as in the reader, add too much food into the system the uneaten food will rot or the fish will become sick from eating too much, though the fish will be sick if ammonia is in abundance. The rotten food adds unneeded ammonia into the system as well as potential pathogens and a sink in oxygen due to decomposition. A good rule is if the food is not eaten by five minutes do not feed the fish anymore. If too much food is given I would suggest adding a water plant, such as duckweed, to the system; this also gives the fish extra oxygen to breathe. Plants are not the first to respond to overabundance so they could be overlooked for the average gardener.

Weather conditions are humidity, heat and ventilation, for plants. Ventilation is adequate in the greenhouse and water is flowed through the system, providing moisture. The conditions conducive to plants are nearly the same as fish being used. “The best temperature for tilapia is they do best in “70-88f, with 77-84 typically being the sweet spot for fastest growth.” (Hatchery Manager of White Brook Tilapia Farm)

How and what plants are grown is another important issue that growers face. The cheapest seeding method in use for media based systems is simply sticking them in the media, on the water line. There are other types of seed starting. One such is media plugs, commonly used in non-media based systems such as deep-water-culture and NFT. Plants that are successful with aquaponics are anything from water-cress to papaya. So as long as a media bed is mature you can grow a fruit tree, which is the consensus in the newly emerged informal research, though it is in need of further study. However a single lettuce plant uses fewer nutrients than an entire tomato bush, so that should be in consideration.

How the plants/fish are grown, what can be grown, and to what degree they can be grown, is largely dependent on water quality. Water quality in aquaponics is most defined by dissolved oxygen, nitrate levels, nitrite levels, ammonia levels, pH, and minerals present. A common measurement for aquaponics is ppm. PPM is literally parts, the thing measured, per million. In nitrate testing kits the ppm is set to a pigment and the pigment can be used alone. Nitrite, nitrate, and ammonia/ammonium are measured in ppm (g/L). Testing for the nitrogen in the system may only require a nitrate test kit and careful observation. Dissolved oxygen is important because both the plants and fish need oxygen for respiration. Fish gasping for air is a good indication that DO levels are too low. In fact, too good, the fish’s respiratory system is in danger at this point. pH is -log of the H ion or how many hydrogen ions there are in matter. The scale is 0 to 14, where below seven is acid and above seven is alkaline (basic). It should be noted that 6 is much more acidic than 6.8. A good pH for aquaponics is about 6-7 while, roughly, a pH above 7.2 will lock out some nutrients, a pH in the 5’s will start to harm life, and a pH above 8 will kill most things, except the biofilter. A high pH should be corrected, slowly, with pH down or another acid, a low pH should be cured with a bag of seashells inserted into the system for a few hours, testing regularly should occur while this task is being done. (Adding strong bases is recommended if you have experience with it. Good strong bases include KOH, NaOH, Ca(OH)2, CaO, MgO and others. It depends on your experience with strong bases and cost. As for acids, a good strong acid is HCl, because the Cl ion will coat the fishes gills to prevent Nitrite and Nitrate ions from poisoning the fish, another good, strong acid is  Phosphoric Acid. Again, experience and cost will determine the acid that works best for you.) 

In addition to the nitrogen cycles effect on water quality a different bacteria type is an anaerobic bacteria, they are denitrifying as opposed to nitrifying. The environment in which they live are anaerobic environments, so maintenance may be required for all types of systems.

Chlorine is another important water quality issue, but should only be a problem if you leave the tap running all day. Reports of tilapia surviving this kind of catastrophe have been talked about. The best way to add tap water to an aquaponics system is to let it outgas before entering. Chlorine will leave the holding tank via evaporation and clean water is left, assuming the water doesn’t have other variables involved.

The benefits of aquaponics are astounding. Benefits of aquaponics are, less water usage, 2-10% less, it can be in a controlled environment, it can be implemented anywhere, and it doesn't abuse the depleted soil. However fossil fuels may come into play because of energy costs, but aquaponics uses significantly less fossil fuels than conventional farming. Tractors and fertilizer play a large role, transport is a problem too. Furthermore aquaponics has a significantly less foot print, so the efficiency is high. Aquaponics has been considered by many to be useful for their purposes and in a recession a low cost alternative to “healthy” foods are needed. A combination of soil and soilless can achieve low costs needed for the economics of systems.

Considering the benefits the basic things a person needs to build a system are H₂O pump(s), an O₂ pump, airstones, container for fish (barrel), container for media (recycled materials), media(pea gravel), plastic tubing, and adjustments (the fish and plants are required too). This is a barrelponics system, invented by Travis Hughey.