Biofertilizer Aquaponics & Biochar

Biofertilizer Aquaponics  & Biochar

Biofertilizers (also known as “plant-growth promoting rhizobacteria” or PGPR) have come on rapidly in “sustainable” agricultural circles, providing eco-friendly organic agro-input. A biofertilizer contains living microorganisms which, when inoculated into biochar or soil, promotes growth by increasing the supply or availability of major nutrients, such as Nitrogen and Phosphorus. Bio-fertilizers add nutrients through the natural processes of nitrogen fixation, solubilizing phosphorus, and stimulating plant growth through the synthesis of growth-promoting bacterial bio-liquides. Bio-fertilizers do not contain any chemicals. Using Biochar in conjunction with aquaponics is a cutting edge innovation. Biochar has proven to be many times more useful as a medium than rocks. This is true especially when considering applications and/or inoculations with beneficial microorganisms. This is mainly due to the porous structure of Biochar which supports microbial communities. Due to immobilization of phosphate by mineral ions such as Fe, Al and Ca or organic acids, the rate of available phosphate (Pi) is always below plant needs. In addition, chemical Pi fertilizers are also immobilized in the soil, immediately, so that less than 20 percent of added fertilizer is absorbed by plants. Therefore, reduction in Pi resources, on one hand, and environmental pollutions resulting from both production and applications of chemical Pi fertilizer, on the other hand, have already demanded the use of new generation of phosphate fertilizers globally known as phosphate-solubilizing bacteria or phosphate...

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Understanding the Ups and Downs of pH

Understanding the Ups and Downs of pH

Bottom Lines of pH in an Aquaponic System The experts vary in defining the “perfect” pH in an aquaponics system. Murray Hallam of Australia, places it lower than most, from 6.2 to 6.4. He feels it is the best pH for fish, while  still in the ballpark for microorganisms. Most other experts prefer a higher pH in order to focus on the bread winners, the plants. One such aquaponics expert I like to quote is Dr. Wilson Lennard. His mark to reach in pH is 7.0 to 7.2. Distilled, Rain water or water made from a reverse osmosis method will not have any dissolved salts carrying ions in your tank. But if you are starting with tap water, well water or water from a lake or pond, there will be mineral salts dissolved. In these waters you will have some dissolved minerals that effect your waters pH quite a bit. This is called “hardness”.  There are bits of information we all need to know about hardness. There are two types of hardness. The first type is carbonate hardness, referred to as KH, alkalinity of BUFFERING CAPACITY. The second type of hardness is called general hardness or simply GH. The GH refers to the concentration of calcium and magnesium ions in the water. It is the buffering capacity, KH that effects pH factor more. The buffering capacity acts like sponge soaking up acids or bases is in your tank or is added to your system. The newly added ions will not effect your waters pH until that sponge (the KH0 is saturated and full. Add all the acids or basses you like but the pH wont budge. Burt when it does reach it’s limit, a very small addition of base/acid will start effecting your levels. That is why many times you can add a bit of acid (for example) and the pH doesn’t budge. You do it again and again with the same results. Then all of a sudden you add one more drop and the numbers fall off the cliff.  So the best way to imagine what happened is that you ‘filled up’ the sponge. KH levels are measurable. Knowing your KH will help you manage your pH. The larger the KH number, the more resistant your tank water will be to a pH change. You can measure your KH if you have a KH meter.  They give readings in dH (degree hardness) Having a higher KH level can be beneficial in a fully cycled system. This is because the nitrification process’s byproduct is nitric acid. This steadily produced nitric acid steadily drives your pH down into acid ranges, in an unbuffered environment. A rule of thumb is that a KH of less than 4.5 dH means that you don’t have much buffering capacity and you should be checking your pH a lot more often. You can increase your system’s buffering capacity by add calcium and/or potassium carbonate, a little at a time. Over time, you will build an solid buffer and your system will become more and more pH...

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Testing pH and Temperature | Aquaponic System

Testing pH and Temperature | Aquaponic System

Besides amonia-nitrate, pH & temperature are the two most important parameters that should be tested regularly   Testing pH in an Aquaponic System An aquaponic systems needs to find a compromise between optimal pH requirements of the fish plants and bacteria because all are somewhat different. The optimal pH for fish, plants and bacteria are: fish- 6.5 – 8.0, plants- 4.5 – 7.0, bacteria- 6.0 – 8.0. Therefore, the best pH to aim for in your aquaponic system is between 6.7 to 7.0 pH.  This compromise is good for the fish. It makes sure the ammonia is low and ammonium high. Refer to the diagram below. This compromise in pH is also good for the for the plants. It’s in a range that their needed nutrients are mostly available. Lastly, it is good for the bacteria. You can test the pH with an inexpensive pH test kit from an aquarium store. The brand I find most accurate and convenient is the API Freshwater Kits, using liquid drops in the test tube they provide. There are more sophisticated pH meters. If your in it for “keeps”, you should make the investment. Hanna is a well known brand. A Hanna Como pH-ppm meter is standard equipment for me. They have Nitrate-Amonia meters as well. Testing Temperature in an Aquaponic System Plants have a wide range of temperature tolerance. But it is best to monitor temperature ranges for the health of your fish as well as your beneficial microorganisms in your growing media. Different fish will have different optimal temperature ranges. For example Talapia aurenus has a wide range it can survive in (8′ to 30’C), however 20 to 24’C is optimal. You need to be familiar with your particular fishes optimal range. Fish could have digestive problems at temperatures above or below their optimal range. But another very important factor concerning water temp is the pH.  With water temperatures outside the optimal range, the bacteria which covert your ammonia into usable Nitrate will loose efficiency  and slow in this nitrogen conversion. The fish may then be subject to dangerously high ammonia levels that are toxic to the fish.  ...

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Adding Potassium and Calcium | Aquaponic System

Adding Potassium and Calcium | Aquaponic System

Aquaponic Systems that are operating in an aerobic condition, the nitrification which converts Ammonia into Nitrite then Nitrate, has a continuing falling pH. Therefore a buffer must always be added to keep the pH at an ideal 6.7 to 7. It is the addition of these buffers that can allow the operator to add a Potassium and or Calcium buffer. Both elements are always missing in an aquaponic model. Fish do not require the same amount of these 2 important plant nutrients, Potassium- K and Calcium- Ca. You will never find these two elements in fish foods. Therefore it is never added to the tank unless added over and above the food given to the fish. So these two elements should always be used to adjust pH in aquaponic systems instead of another form of an alkaline...

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Aquaponic Feeding Rate Ratios

Aquaponic Feeding Rate Ratios

The following article is based on Wilson Lennard PhD’s Aquaponic System Design Parameters Aquaponic fish to plant ratios, which is directly related to aquaponic feeding rate ratios, is the heart of a well performing unit. There are many approaches that attempt to define how many fish to place in your particular system and how much food to feed your system’s fish. Unfortunately many of these approaches are incorrect and have no real association with correct ratio determination methods for aquaponic systems. But there are two scientifically based approaches that will help get us on the right track. The UVI/Rakosy approach and the Aquaponic Solutions/Lennard approach. A third well based approach has also surfaced recently as well. Defining Aquaponic Design Ratios How do we size-up the two major components in a system, the fish and the plants? A common but partially unfounded method is to simply draw a relation between the amount of water or fish in the fish compartment and the amount of media in the growing beds. But if we were to look at what is actually occurs in an aquaponic system, we can get a better understanding of a more appropriate method. We are aware of the aquaponic principal that the fish are fed, the fish produce wastes and this waste is used by plants for their growth. The amount of waste produced is in direct proportion to the amount of fish food consumed by the fish. The amount of plants that can be grown is proportional to the amount of nutrients available which in turn depends on the amount of waste produced by the fish. This in turn is dependent on how much food is fed to the fish.This is an uncomplicated circle of proportions. So the only real predictable ratio is based on the amount of fish feed entering the system related to the number of plants we grow. SO in actuality the ratios should be determined not by water nor media quantities but by the two major components of an aquaponic system… the fish and plant components. Therefore, in actuality the ratios should be determined not so much by water nor media quantities but by the two major components of an aquaponic system… the fish and plant components. Steps in Determining the Feeding Rate Ratio Simply stated, the feeding rate ratio is how much fish food we need for the number of plant in the system. To get there, answer the following: How Many Plants you would like to produce How Much Area the plants need to grow How Much Fish Feed the fish need to produce enough nutrients for those plants What Amount of weight of fish are required to eat that much fish food. What Volume of Water that amount of fish need to be happy. The fish-feed amount and the plants being grown is the Feeding Rate Ratio. As with any plant you grow, you need to give it nutrients. The nutrients are indirectly supplied by the fish food. The UVI/Rakosy Approach Dr. James Rackocy of the University of the Virgin Islands began some 30 years ago studying Aquaponic Systems.  His approach is measured in grams of fish feed/square meter of plant growing area per day. His bottom line using this formula is very general, which helps beginning operators to keep it simple. His bottom line formula is: 60 to 100g/m2/day One of his most important observations was that fish have different requirements than plants as far as nutrition. The main differences are: Fish do not require the same amount of 2 important nutriens which plants do: Potassium- K and Calcium-...

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Ammonia vs Ammonium

Ammonia vs Ammonium

“Ammonia-nitrogen” includes the ionized form (ammonium, NH4+) and the un-ionized form (ammonia, NH3). Ammonium is produced when microorganisms break down organic nitrogen products such as urea and proteins in manure. This decomposition occurs in both aerobic and anaerobic environments. One of the noticeable differences between the two is that Ammonia gives out a strong smell whereas Ammonium does not smell at all. Ammonia (NH3) is an actual gas or liquid you can see. It is not ionic. When ammonia goes ionic, which happens when you add ammonia to water, it draws a hydrogen away from a water molecule to form ammonium (NH4+). The chemical equation that drives the relationship between ammonia and ammonium is: NH3 + H2O ↔ NH4+ + OH- The un-ionized Ammonia with the formula NH3  is a weak base. The iodized Ammonium with the formula NH4+, is an acid. In solution, ammonium is in chemical equilibrium with ammonia. The major factor that determines the proportion of ammonia or ammonium in water is water pH. When the pH is low, the reaction is driven to the right, and when the pH is high, the reaction is driven to the left. This is important as the unionized NH3 is the form that can be toxic to aquatic organisms. The ionized NH4+ is basically harmless to aquatic organisms. Ammonia exerts a direct biochemical oxygen demand (BOD) on the receiving water since dissolved oxygen is consumed as ammonia is oxidized. Moderate depressions of dissolved oxygen are associated with reduced species diversity, while more severe depressions can produce fish...

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