Here's a Quick Way to Prevent Toxic Ammonia Levels

What is a safe level of ammonia in an aquaponic system?  This question elicits more incorrect responses, confusion and frustration than any other topic in aquaponics.  Why?  Because new growers are not instructed on how to interpret water quality readings together to evaluate toxicity.

Ammonia, when dissolved in water, becomes partially ionized.  The ionized ammonia is called Ammonium \(NH_4^+\) and is not toxic to your fish.  Non-ionized ammonia, often referred to as "free ammonia" (\(NH_3\)), is highly toxic in low levels.  From this you need to know two very important things.

  1. Of the two most common water quality test kits, neither provide a reading of free ammonia.  Instead they provide a reading of total ammonia nitrogen (TAN), ammonium or both.
  2. Free ammonia is a function of \(pH\), water temperature (\(T\)) and \(TAN\).
$$ NH_3(pH, T, TAN) $$
In other words, a free ammonia evaluation requires pH and water temperature in addition to an ammonia reading in order to get an accurate assessment of toxicity - it cannot be determined solely on the ammonia water quality reading. To prevent ammonia toxicity, track and then evaluate \(pH\), \(T\) and \(TAN\) using the calculator below. The question of safe ammonia levels should be interpreted as, "What is a safe level of free ammonia in my aquaponic system?" The free ammonia calculator below uses the following scale, based in part on reports from the EPA:
  • Safe:  \(0 \le FA \le 0.019\)
  • Danger:  \(0.020 \le FA \le 0.030\)
  • High Danger:  \(FA \ge 0.030\)

Did you find this tool useful?  Let us know in the comments below.

Plant Nutrition: Essential Elements for Plant Growth

Plant nutrition is a diverse topic ranging from an understanding of the parts of a plant, essential elements plants need, the methods by which nutrients are absorbed and physiological symptoms of nutritional disorders.  This article, part of a series on each of these topics, focuses on the essential elements of plant nutrition.

Plant nutrition is at the core of food production techniques such as gardening, aquaponics and hydroponics.  In aquaponics the nutrients are provided as a by-product of the aquaculture, which is composted by natural bacteria.  Hydroponics, in contrast, requires the essential nutrients to be dissolved in water (or a concentrated solution of these nutrients to be diluted in water) and then the nutrient solution is made available to the plants.  Organic gardening can use recycled plant fibers that have been composted.  Regardless of the method you use, a thorough knowledge of plant nutrition is critical to managing your crops.

Essential elements necessary for plant growth are split into three categories: essential mineral elements, essential nonmineral elements and beneficial elements.  The criteria for elements to be considered essential was first set forth by Arnon and Stout in 1939:
  1. The element must be required for the completion of the life cycle of the plant
  2. The element must not be replaceable by another element in whole
  3. The element must be directly involved in the metabolism of the plant, i.e. required for a specific physiological function in the plant.
Water makes up the majority of the plant fresh weight, from 80 to 95 percent, with the exact percentage dependent on environmental and nutrient conditions at the time of analysis. Of the 90+ naturally-occurring elements found in plant tissues, only 16 are considered essential for plant growth. The first three are the essential nonmineral elements and they are, with their corresponding concentration in dry plant tissue:
  • Carbon, 45%
  • Oxygen, 45%
  • Hydrogen, 6%
Carbon is supplied from carbon dioxide, oxygen from both carbon dioxide and water, and hydrogen from water.   As you can see oxygen is one of the most abundant elements in plants and it is the access to oxygen that set growing methods like aquaponics apart from traditional dirt farming.  The growing medium can range from gravel, sand, light expanded clay aggregate (LECA), rockwool, sawdust, vermiculite and others.  The growing media only serves four purposes for plants: supply of water, oxygen, essential nutrients and supports the plant root structure.  By using a growing medium that cannot be compacted like soil, plants roots have increased access to oxygen and carbon dioxide, producing larger, more vibrant and productive plants.

The essential mineral elements comprise the remaining essential elements and are further divided into two categories, macronutrients and micronutrients.  The macronutrients and their relative percentages in dry plant tissues are:
  • Nitrogen, 1.5%
  • Potassium, 1.0%
  • Calcium, 0.5%
  • Magnesium, 0.2%
  • Phosphorus, 0.2%
  • Sulfur, 0.1%
The micronutrients are:
  • Chlorine, 0.01%
  • Iron, 0.01%
  • Boron, 0.002%
  • Zinc, 0.002%
  • Manganese, 0.005%
  • Copper, 0.0006%
  • Molybdenum, 0.00001%
Beneficial elements can promote plant growth, but fail to meet Arnon and Stout's criteria of essential.  They are silicon, nickel, sodium, aluminum, cobalt, selenium and vanadium to name a few.  Each of the essential elements has a role in the life of the plant, from regulating biochemical reactions to food storage to various metabolites for plant growth.  It's important to note plants have the ability to absorb a wide variety of elements present in soil.  The danger of pollution is plants are capable of absorbing toxic elements it may not actually use in development and growth.  Regardless, the toxicity of the element is not mitigated once absorbed by the plant and poses the same health risks should the plant be consumed.  A brilliant new scalable green technology has emerged to take advantage of this basic premise.  Called grey water reclamation this technology allows water polluted by anything from waste to heavy metals to be filtered using plants, which then absorb the elements.  The filtered water is then recycled back into the system.  The applications have ranged from shower and toilet water in homes, to grey water in office buildings.

The top three limiting nutrients, from a crop production standpoint, are nitrogen, phosphorus and potassium.  It was Justus von Liebig who developed the Law of the Minimum which states that crop yield is proportional to the amount of the most limiting nutrient, whichever nutrient it may be.  Once the deficient nutrient is provided, crop yield may increase until another nutrient becomes deficient and the Law of the Minimum would then apply to that nutrient.

Nitrogen is arguably the most important of the nutrients in an aquaponic system.  It is absorbed by plants as either ammonium ions or nitrate ions and then further reduced into organic compounds.  The fish by-product is primarily ammonia, a combination of ammonium and toxic free ammonia.  The bacteria cycle breaks down free ammonia to create nitrites and then nitrates.  In plants, nitrogen is an essential component of amino acids, the building blocks of proteins, which can be used in the structure of the plant, and nitrogen can be found in enzymes and coenzymes, which regulate the biochemical reactions in plants.

Phosphorus plays an important function in energy transfer in plants, specifically in the formation (and reduction) of phosphate bonds in ATP, a chemical energy compound.  The phosphate bonds needed to form ATP are produced via photosynthesis, while the energy processes required to grow the plant break down the bonds for the energy stored in them.  All cell membranes in plants comprise a lipid structure containing phosphorus which regulate the flow of compounds in and out of the cell.  Phosphorus is also part of the sugar phosphates which form structural components of nucleic acids DNA and RNA.

Potassium is absorbed as a cation and with only one oxidation state it balances the uptake of anions such as nitrate, sulfate and chloride.  It is also used as an activator for many enzymes and is required in high levels for protein synthesis, however it does not form a structural part of the plant.

The mere presence of the essential elements does not guarantee their availability to the plant.  The pH level of the aquaponic system dictates the rate at which the nutrients are absorbed.  pH is a measure of acidity and alkalinity.  As a logarithmic function, a one-unit change in pH is a ten fold change in hydrogen ion concentration.  Note in the chart below that Resh's optimum pH range is based on the hydroponic growing system, not aquaponics.

pH affect on nutrient availability.  Resh 2001.
This chart can be invaluable in diagnosing nutrient deficiencies in plants.  As an example we can see that as pH rises from 6.0 to 8.5 (a dramatic increase by any standard) we find a decrease in the amount of iron, manganese and boron available.  Plants requiring significant percentages of these elements would show some physiological symptoms of nutrient deficiency.  It is important to catch an imbalance early, since a deficiency of one element can impair the plant's ability to accumulate other elements.  In this case, the physiological symptoms characteristic to a single element deficiency are obscured with the symptoms of another, making it almost impossible to determine which elements are causing the deficiencies.

An excellent technique to detect nutrient deficiencies is to place different plant species with varying levels of susceptibility in the same system.  A common example is planting cucumbers in the same system as tomatoes.  Cucumbers will manifest symptoms of calcium deficiency long before tomato plants will.  While you may lose the cucumbers, you can remedy your system before losing your tomatoes.  The value of this technique is that you may still have a productive harvest instead of losing your entire crop.

In the chart above, Resh's pH range is selected to optimize nutrient uptake in a hydroponic system where plants are the only living component.  In aquaponics, however, we have three different living systems present: fish, plants and bacteria, each with a different optimum pH range.  We compromise and come up with an optimal range of 6.7 to 6.9.  This is very important to note.  Since the overall pH of the system is outside the ideal range of a particular component, smaller fluctuations in pH can have a bigger impact.  That is why pH is one of the key parameters to be monitored using programs like Aquaponics Tracker.  For example, if a pH fluctuation shifts outside the acceptable range for the bacteria, the bacteria may go dormant (or die), preventing the conversion of fish waste to plant nutrients.  The plants will begin to show symptoms of nutrient deficiency, but more importantly the lack of bio-filtration means accumulating toxic levels of ammonia in your fish tank.  When keeping track of system parameters it is important to assign notes to your system readings, such as tracking physiological changes in plants and fish, to link symptoms with readings and allowing you to check back should a similar incident arise again.

As I stated at the beginning of this article, understanding plant nutrition is required for managing your system.  By understanding the role nutrients play in plant development and health you have a powerful tool to diagnose physiological symptoms of plants in your systems.  While you are relieved from the careful measuring nutrient salts to dissolve in water required by hydroponics (or diluting concentrated solutions from bottles), you are responsible for the feed you provide your fish.  If your fish are denied proper nutrition, they in turn will create a poor by-product to feed your bacteria.  Always remember, "Garbage in, garbage out."


Primal Aquaponics

The Primal Blueprint.  Paleo/Paleolithic/Caveman/Stone Age Diet.  Neanderthin.  These are all lifestyles or diets advocating a return to consuming foods grown/raised in the manner in which they evolved.  For example, consuming beef that is grass-fed instead of corn fed, as cows evolved to eat grass and must be given antibiotics to process corn.

While I laud the "return to nature" philosophy, and I myself follow the Primal Blueprint, there are a few major problems common to all of these lifestyles.  The diets are designed based on the presumed foods of paleolithic humans.  Emphasis on presumed.  In fact, the difference of opinion on just what paleolithic humans ate is why we have the different diets.

Proponents argue humans have been evolving for millions of years on a certain diet and with the advent of agriculture only in the last 10,000 years, we have not had enough time to evolve to eat these new crops.  While I agree agriculture is the root of today's health problems, I disagree with the premise it is a time issue.  The tomato of today is a far cry from what it was over 10,000 years ago and I think the same can be said of most mass-consumed crops; they have been cross-bred or genetically altered.  If humans haven't evolved to eat soybeans in the last 10,000 years, they certainly haven't evolved to eat genetically modified soybeans that have only been around since 1996.  The time to evolve becomes irrelevant as we continually introduce new versions of genetically mutilated seeds.  The "clock" is constantly reset.  

This brings up a second problem with these lifestyles - sustainable sources of quality, clean, foods.  For instance, the Primal Blueprint advocates consuming wild vs. factory farm salmon, but as more people learn the benefits of salmon, salmon become over-fished.  In Alaska many salmon come from hatcheries and are then released into the wild in order to ensure the salmon stock.  Nature cannot keep up with demand so we develop Concentrated Animal Feeding Operations, (CAFOs) for the seas.  Primal followers are well aware of the laundry list of problems CAFOs have introduced.  

These days I feel "wild" is more of a marketing gimmick.  I have yet to come across a stream/river/pond/lake that doesn't have some sort of pollution in it.  There is an enormous garbage patch out in the Pacific Ocean.  We have polluted the environment to an extent I think most marine life has been exposed in some way.  I'm not interested in eating wild-caught anything that has been living in such a polluted environment.  

Photo: Scripps Institution of Oceanography
We are very particular in purchasing grass-fed beef, but cattle aren't the only thing being fed subsidized GMO grains.  Chinese fish farmers are now feeding soy to fish.  What is the future of fish being fed something so foreign?  It's going to get harder and harder to find clean foods.  

I started in aquaponics because I needed a source of nutrient-dense foods that I could ensure were available year round, local, but just as importantly, it had to be sustainable, highly productive with little to no impact on the environment.  The food needed to be clean to ensure the health of my family.  Aquaponics is not just a solution, but the ideal solution for Primal/Paleo followers.  It is a closed source ecosystem that doesn't mimic nature - it is nature. Think about it:  It's mid-January and you are preparing your 2 Minute Primal Salad with ingredients grown in your own home.  You aren't running to the store for produce that is more expensive this week because of a drought in Mexico.  You don't have to worry about purchasing old produce from two weeks ago because the re-supply trucks haven't arrived yet.  And forget about those tomatoes that were picked before they were ripe and ripened en-route to you with gas.

Aquaponics is a highly productive, year-round means of growing nutrient-dense foods using the same methods nature employs, but in your own home.  It's the best mix of nature and 21st century technology with a true Primal intent.


Aquaponics Taste Test

This is a first.  A blind taste test of aquaponic vegetables vs. garden grown was done using  professional chefs.  Three different varieties of lettuce were evaluated.  The judging categories were place of origin, appearance, aroma, flavor and finish.  Garden-grown just barely edged out aquaponics.

Read more


The Vertical Farm

Eco-Laboratory by Weber Thompson.
The first time I came across the Vertical Farm concept, it was in an issue of Popular Science.  A large pullout showed an awe-inspiring skyscraper with a white-bearded man posing in front, cupping an ear of corn and staring off in the distance.  The Future of Farming.

Upon hearing of aquaponics I was immediately reminded of that pullout and dug out my old PopSci issue.  A few days later I checked out, "The Vertical Farm," by Dr. Dickson Despommier, from my local library.

"The Vertical Farm" is a two part book.  We start off looking at the past and current state of agriculture, coming to the conclusion it is failing to provide nutritious foods, it is insufficient to sustain us in the future and the ecological destruction caused my modern farming methods has taken an incredible toll on the planet.

Dr. Despommier's solution is to utilize skyscrapers to grow food hydroponically in the middle of cities.  According to Dr. Despommier, the vertical farm has a number of advantages over traditional agricultural methods.  In the remainder of this article I discuss his proposed advantages and in my next article I will argue aquaponics not only has these benefits, but it takes them to a whole new level and then adds more.

"The Living Skyscraper:
Farming the Urban Skyline"
by Blake Kurasek
1.  Year-round crop production.  By growing crops inside controlled environments, crop production is not dependent upon the seasons.  Instead of one season of tomatoes, staggered planted tomatoes can be harvested year round.

Related:  CEA and grow lights

2.  No Weather-related Crop Failures.  As I write this, the corn crop in Iowa is in trouble.  There has been very little rain this season and the crops have suffered accordingly.  By growing foods in controlled environments, droughts, floods, hurricanes, tornadoes and other natural phenomena are irrelevant (assuming the vertical farm survived the tornado).  The world will feel the effects of the drought in corn country since products from Coca Cola to Starbucks, ethanol to beef all contain corn products and the increased price per bushel of corn is going to permeate the global economy.

3.  No Agricultural Runoff.  "According to the USDA, Agricultural nonpoint source pollution is the primary cause of pollution in the U.S." - The Vertical Farm.  Soil is composed of pesticides, herbicides, fungicides, rock, etc. and when it rains the runoff inevitably ends up in streams and heads down river.  By growing hydroponically in a controlled environment, these toxic chemicals are unnecessary.

4.  Allowance for Ecosystem Restoration.  The first part of The Vertical Farm talks about the current state of the ecosystem, specifically how poor a state it is in.  By moving agriculture into city skyscrapers, Dr. Despommier argues traditional agriculture won't be necessary and the land can be turned back over to nature to recover.

5.  No Use of Pesticides, Herbicides, or Fertilizers.  Guess what?  There are no weeds to pull in hydroponic/aeroponic/aquaponic systems!  Dr. Despommier argues hydroponics is a superior method of growing foods; by adding only the nutrients the plants need to the water the plants live in, a balance is achieved.  The plants absorb all the nutrients and clean the water.  The nitty-gritty details on this point are really where aquaponics and hydroponics shine as an alternative to traditional agriculture.  But I disagree with Dr. Despommier on this point and believe aquaponics is a far superior method to hydroponics.

6.  Use of 70-95 percent less water.  According to The Vertical Farm, "Today, traditional agriculture uses around 70 percent of all the available freshwater on earth, and in doing so pollutes it, rendering it unusable for those living downstream." Water is by far the most precious resource on Earth. The pollution of our water by traditional agriculture is the primary need to alter our farming methods. Of all the benefits on this list, this is the most important.

7. Greatly reduced food miles. A common argument for alternative farming is that the average distance food travels from farm to table is 1500 miles. That is a staggering number! The Vertical Farm proposes growing food in the center of cities, drastically cutting this distance down. I propose an even greater reduction in food miles by growing food at your home!

8. More Control of Food Safety and Security. The Vertical Farm is designed using the same equipment hospitals use in intensive care units to prevent pathogens and pests from affecting the crops. Security is proposed to prevent people from sabotaging the environment.

Artist's rendition of a
desertVertical Farm
9. New Employment Opportunities. When farming exists in a skyscraper there are plenty of job opportunities. The traditional farmer goes through stages: they buy their seeds, tills, fertilizes, plants, maintains, harvests and sells. In the Vertical Farm, the crops exist in all of these stages all the time, necessitating the need for labor.

10. Purification of Grey Water to Drinking Water. Grey water reclamation will become an even hotter topic as the scarcity of clean water becomes more desperate. Plants provide a natural (bio) filtration process that can clean toxins out of the water. Clean water from plant transpiration can be recovered using dehumidifiers. While you can't eat the plants, Dr. Despommier argues the plants can be incinerated using plasma arc gasification to create energy.

11. Animal Feed from Post-harvest Plant Material. You don't eat all parts of a plant and what is leftover can be used as animal feed. I argue you can take this one step further and suggest you could also compost this material for seedling beds.

Wow, those are some good arguments!  

Overall, I thoroughly enjoyed reading The Vertical Farm. But there are problems here. Firstly, and even Dr. Despommier freely admits, you need to suspend your belief any government will sponsor a vertical farm. States are so strapped for cash, projects like this, on the scale proposed, are pipe dreams. I find it hard to believe a project like this will ever be subsidized, a need the author believes is necessary.  

Second, if the project did get off the ground, the costs are staggering to the point the product may not be affordable. The price drives consumer choice. Yes, there are niche demographics that are willing to pay a premium for a premium product, like customers of farmer markets or Whole Foods. I must say, I feel different now shopping at a store like Whole Foods. I might buy avocados grown in a sustainable way, but they are grown in Mexico. Is it really better to buy foods grown so far away? Do the benefits offset the the food miles? I don't think so. Enter the birth of groups like The Hundred Mile Diet.

The Vertical Farm - Dr. Dickson DespommierWhen I finished The Vertical Farm I admit I was disappointed. Like Food, Inc. I was left with the question, "What can I do now?". I want to buy foods that are better for my family, better for the environment, better for society. How am I supposed to source locally grown organic tomatoes in January?

But there is an even better method than the vertical farm, a more sustainable method, that takes these advantages to a whole new level and I will show you what you can do right now.

Related:  Grow Lights and Automation


Need help monitoring your aquaponics system?  Check out Aquaponics Tracker, an Android app for keeping tabs on the key parameters that keep your system healthy.

Vandana Shiva on the Problem with Genetically-Modified Seeds

Vandana Shiva, an Indian physicist and anti-GMO activist, was on Bill Moyers today.  Shiva very succinctly challenged the common belief genetically-modified crops (GMO crops) are safe for consumption and safe for the environment.  She argues against the use of genetically modified seeds, claiming they are more costly morally, economically and ecologically.  Here is a description:

Bill talks to scientist and philosopher Vandana Shiva, who’s become a rock star in the global battle over genetically modified seeds. These seeds — considered “intellectual property” by the big companies who own the patents — are globally marketed to monopolize food production and profits. Opponents challenge the safety of genetically modified seeds, claiming they also harm the environment, are more costly, and leave local farmers deep in debt as well as dependent on suppliers. Shiva, who founded a movement in India to promote native seeds, links genetic tinkering to problems in our ecology, economy, and humanity, and sees this as the latest battleground in the war on Planet Earth.

Vandana Shiva Interview