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Rodney has been a member since June 29th 2012, and has created 36 posts from scratch.

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Cairns Man “Aquaponic Gardener” recognised by the Head of State, Queen of England

shaking Governal Generals hand

Rod Ingersoll shakes the Governor General of PNG’s hand after being awarded OBE

Just a quick blog post to alert my aquaponic sustainable minded gardening friends that as an Australian Citizen working in remote Papua New Guinea highlands, my commitment to the people of Papua New Guinea and community/ environmental work history was recognised by Her Majesty Queen Elizabeth 11,  Queen of Great Britain and Commonwealth, at a ceremony at Government House, Port Moresby last week (23/11/17).

His Excellency, Grand Chief Sir Bob Dadae, Governor General of Papua New Guinea confirmed the title “Most Excellent Order of the British Empire (OBE)” for my Community Development, Rural Health & Environmental Conservation achievements to date. I’m glad i was able to borrow a suit. Its sure not my usual clobber. I’m much more comfortable in the tropical forests of Australia and PNG playing with frogs, tree kangaroos and birds of paradise wearing my usual khaki green and hat.

“I am overwhelmed and speechless to be recognised in this manner by the PNG Government and Her Majesty the Queen of England”.

OBE Award conferred to Rod Ingersoll

Rod Ingersoll receives OBE award from Governor General of PNG

“I have worked at the grass roots level with NGOs, government, business & global mining companies. My focus has always been on assisting people and the planet. I’m passionate about building the capacity of PNG communities. If we cant get development assistance right in remote community’s we will never be able to preserve PNG’S unique ecology, especially in mining areas where long term sustainability is difficult to achieve. People need to see a reason to protect their forests for the rest of the worlds sake. Its essential to involve community if you wish to do any activity business or otherwise in PNG”.

“Everyone has something to offer. God has placed us all on the planet for different tasks. PNG seems to be one of mine. I just do what I can, when I can, with what I have & partner with others to get things done. There are a lot of people doing great work around the world, I’m just one person doing my bit on a big planet”.

“I personally still have big dreams and visions for PNG. With Climate change impacting Agriculture and people’s ability to grow food, the need surrounding mining areas and very little of PNGs tropical forests protected, think I might stay for a while longer and see what else may need doing”.

“I truly believe that we can all make a difference. Its not hard. You don’t have to go to another country like i did. Everyone’s voice is valuable right where you are, everyone has something to offer those less fortunate than ourselves. Do what ever you think you are called to do and then take massive action”.

“Everyone can positively influence their own backyard and own community. Grow your own vegetables to reduce food miles, plant a tree to attract biodiversity, don’t buy a certain product if old growth forests were logged to make it for example toilet paper or furniture. Here’s a big idea- talk to your next door neighbor to make sure they are OK. Just make some kind of effort to help humanity and the world we live in. If we don’t each do something, the repercussions are long term and endless”. 

“It hasn’t always been easy and I have sure had many challenges both in Australia and Papua New Guinea but anything worthwhile always has a few bumps in the road. Important thing is to stay focused on the positives, dig deep, find the strength to continue and celebrate the people’s lives being changed by even smallest of environmental , community or agriculture projects”. 

“Its been a wild 41 years journey, best years are always ahead, “ Mr. Ingersoll said.


Rod Ingersoll Honoured by Queen with OBE

Cairns Post 29th Nov 2017- Feature article- “Ecologist honored by Queen for PNG Work” (click to enlarge)

Look at Aquaponic Macro & Micro nutrients

When I first heard how aquaponics used fish waste to provide nutrients to plants, one of my first questions was how does it work? What are the processes at work that allow this relationship to flourish on both sides? I understood the general theory. The fish eat, the fish produce waste from their food, the waste fills the water with nutrients, and the nutrients are consumed by plants via roots. The process overall is simple. However, there’s more going on here and that’s where things get interesting.

Just like animals, different species of plants have varying adaptations and unique physical structures. Because of this, every plant will have its own needs as far as concentrations and ratios of different nutrients. That being said, most plants require combinations of the same basic macronutrients and micronutrients, macronutrients being nutrients required at higher concentrations and micronutrients only required in trace amounts. Macronutrients make up the bulk of plant requirements so I’ll focus on those, made up of:

  • Hydrogen
  • Oxygen
  • Nitrogen
  • Phosphorus
  • Potassium
  • Sulfur
  • Calcium
  • Carbon

Aquaponics Nitrogen Cycle


In traditional farming, the most supplemented nutrients via fertilizers are nitrogen, phosphorus, and potassium, or NPK as the ratio of concentrations is labelled in fertilizer solutions. These are the primary macronutrients and the most important in plant growth.

Because the main source of nutrients in aquaponics is fish waste, it’s important to understand how fish produce the waste. It seems obvious that the nutrients are provided by the fish feed and the solid waste associated with digestion. But fish poop is not the only form of waste and it may not even be the most important. Freshwater fish secrete ammonia (NH3), in urea as a waste product, which is absolutely vital to the process.

Ammonia is not what plants consume directly and because Ammonia can diffuse back into the fish, it is highly toxic at high concentrations. A conversion is required and that’s where the third player in the aquaponics game comes into the picture. Nitrifying bacteria are bacteria that convert Ammonia (NH3) into nitrite (NO2), and then to nitrate (NO3). These microbes that carry out the process of nitrification are what keep the system running smoothly. Without them, Ammonia would build up in the solution, nitrates would not be present to feed the plants, and both parties would die. Thankfully these little bugs are found naturally in water.

Thanks to fish urine and bacteria, the N of NPK is taken care of with little effort. However, it is important that oxygen levels in the solution are at adequate levels. In the absence of oxygen, denitrifying bacteria take over and the nitrogen in the system is lost to the atmosphere before it can reach the plant roots. This can be achieved through various forms of air pumps and simply making sure that the system has a continuous flow of running water as it moves from tank to tank.

Most other macronutrients are readily available as well. Oxygen and carbon are pulled from the air and hydrogen is in the water. Phosphorus and Potassium, making up the P and K of the NPK ratio, are slightly more complicated. They’re found naturally in the system however not in large amounts. Because of this, greens such as lettuce, basil, and other leafy crops tend to be favored in aquaponics growth. Plants like tomatoes and cucumbers that require large concentrations of phosphorus in order to form reproductive structures like flowers and fruits may need nutrient supplementation in some systems. There has been success growing all kinds of plants using aquaponics, and this remarkable process is by no means limited to greens.


USA Student Brennan Cross- Cairns Aquaponics Update

Brennan Cross USA student

Mr Brennan Cross- USA University Student studying Australian Aquaponics systems with Cairns Aquaponic Gardener

When designing an aquaponics system, imagination is the limitation. Structure and appearance are highly variable as long as the basic components are provided. The diagram below (figure 2) indicates these components as the rearing tank (where fish are held), solid removal, biofilter, hydroponic subsystem, and a sump.

As the diagram indicates, certain aspects of the process can be combined structurally. From the rearing tank, solid removal may be required before the solution can continue through the system or the system itself can serve as the solid removal. This depends on the organic loading rate (OLR), or the amount of feed input resulting in fecal matter production. If the OLR is high, meaning lots of fish to not as much plant growth area, then the solid removal process must be efficiently done before the nutrient solution can continue. In this scenario screen filters or other filtration methods are used. In systems with lower OLR, less fish and larger growth area, the solution can be fed directly into hydroponic system.

Nitrifying bacteria, discussed in the previous post, serve as the biofilter. They occur naturally in a film that forms on inert surfaces and biomass. They thrive in neutral pH and warm temperatures and are vital to the process as they clean the water of harmful substances and convert them to usable nutrients. The process of biofiltration often naturally works within hydroponic systems.

As the definition of aquaponics indicates, hydroponics is used in collaboration with aquaculture to produce crops of plants and fish. But what exactly is hydroponics? Hydroponics is an agriculture strategy where plants are grown in soilless systems. Nutrients are provided, and consumed by plants through solutions of controlled concentrations. Highly soluble synthetic commercial fertilizer products are often used to mix solutions of carefully formulated combinations of nitrogen, phosphorus, and potassium as well as other micronutrients. In aquaponics, the process is the same except fish feed is the only input. The ability to control and change concentrations of nutrients for different stages of growth is why hydroponics has been so successful and increasingly popular among greenhouse growers.

So how is it done? How are these finely tuned solutions delivered to the plant roots? There are various structures used by hydroponic growers and, again, no limit as to the ways in which they can be modified for certain settings and parameters. But there are three main structures that serve as the basis for all hydroponic systems: Media filled grow beds, floating raft beds, and nutrient film technique.  Each structure has its drawbacks and positives and none are inherently better, rather, each is suited for particular uses and favor some plants over others.


media beds

media beds

Media Beds:

As the name suggests, this structure consists of beds full of growth media fed by a reservoir of solution in a separate tank. Forms of media commonly used are perlite, vermiculite, gravel, sand, expanded clay, peat, and sawdust. Coarser, aerated materials are best, especially in aquaponics. Often, the media bed structure utilizes flood and drain systems to regulate the application of nutrient solution. As the solution is added to the grow beds, it’s distributed evenly throughout the media. There are different ways in which drainage can occur. The most effective are bell siphons and timed pumps.

Bell siphons are extremely useful pieces of hardware that allow a media bed to flood and drain on a regular cycle. A gravel guard creates a pocket in the media occupied by a standing pipe beginning at the maximum water level and leading to the fish tank or sump. At the bottom of the gravel guard, holes allow the water to fill the pocket. A bell cover is placed over the stand pipe. At the bottom of the bell cover are holes allowing the water to rise within the bell cover at the same rate as in the rest of the bed. An air tube runs from the top of the bell to the minimum water level. When the water fills the bell cover and reaches the standing pipe, the pipe acts as a siphon and the bell creates a vacuum which sucks the water from the tank until it reaches the minimum water level. Hence, the bed is filled and drained on a consistent schedule without the use of external energy.

When using media beds, one must consider the efficiency of solid removal. Media beds are susceptible to clogging. If a finer grained media such as sand gets saturated with waste solids, or if the OLR is too high, the grow beds can become deoxygenated and the waste will decompose anaerobically rather than aerobically. This will result in harmful releases of methane and other gases. However, with good drainage, solid removal systems, and well aerated media, this method is a very effective promoter of biofiltration and hydroponic growth.

Floating Rafts:

Floating raft systems consist of sheets of polystyrene that house net pots. This system is ideal for many garden greens such as lettuce, basil, and spinach. Nitrification occurs in biofilm that accumulates on the bottoms of the polystyrene sheets and directly on the roots. Some solid filtration may be required depending on the OLR of the system overall. Buildup of solids on the bottom of tanks can result in anaerobic processes in floating raft system tanks as in the media beds.

Nutrient film techniqueNutrient Film Technique:

The nutrient film technique uses narrow channels to hold plants as a thin layer of solution is applied. This is a useful technique in vertical growing. However, because the surface area and water volume of NFT is considerably smaller than that of both media bed, and floating raft structures, nitrification processes are not well suited within the system and a separate stage for nitrification must be incorporated before the solution film can be applied.




In the end, the result of any of these techniques will be clean, reusable water which can return to the rearing tank and complete the cycle, allowing for happy plants and happy fish.

USA University student studies Cairns Aquaponics system

Hi, my name is Brennan Cross,  an undergraduate university student performing research into the exciting field of aquaponics.

I’m from the United States but thanks to SIT World Learning and the University of Vermont, I have had the opportunity to study here in Australia for a few months at the Redlynch Aquaponics Training Center.

Since I was 14 years old, I worked on a vegetable farm in my Hometown of Simsbury, Connecticut. Naturally over the course of seven summers growing food, I developed an appreciation and interest in agriculture in its different forms. I recently discovered the combination of aquaculture and hydroponics as a sustainable agriculture practice and it immediately piqued my interest.

I met the energetic Rod Ingersoll, aka the Aquaponic Gardener, by chance shortly after arriving in Australia and he’s been kind enough to allow me to perform a modest experiment in his ingeniously designed aquaponics system while I conduct my research.

usa aquaponics research in cairns

USA University Student Brennan Cross conducts Aquaponics research in Cairns

Through a series of installments, I’ll share the results of my research as well as the progress and outcome of my small experiment.

Hopefully I can be of some help to those like me who are interested in how this process works.

I plan to update you with the following over the coming month:





Part 1: Plant Needs and How Fish Provide them;

Part 2: Aquaculture and Hydroponics: What are they and how are they natural allies? (System types and designs);

Part 3: My Experiment Design and setup;

Part 4: Experiment Progress;

Part 5: Results;

Cheers, Brennan Cross






Aquaponic Gardener wins Southern Cross University School of Environment, Science and Engineering Alumnus of the Year 2017

Southern Cross University School of Environment, Science and Engineering Alumnus of the Year 2017 Awards were held in September 2017. Rodney Ingersoll was awarded as finalist for his local and global environmental management & sustainable community development initiatives like aquaponics.

alumni of year 2017

Rod Ingersoll wins SCU Alumni of year 2017

IMG_2845 Alumni065

“I feel numb, happy, humbled & so blessed to have won the Southern Cross University School of Environment, Science and Engineering 2017 Alumnus of the year for services to Global Community & Environmental Management.

So many nominated talented people who have all done so much in there careers. I received the awards acknowledging those who helped me survive university and those who never stopped believing in me. People like SCU Chaplin Rev. John Kidson. I appreciate all your support”, Rod Ingersoll said


See for further information


Jungle Warrior- Aquaponic Gardener Awarded SCU Alumni 2017

Cairns Post  (Cairns eye supplement)- 4th Nov 2017 Feature article- Jungle Warrior (click to expand)