The Water Flow and the Water Valve in our FAO based system

Our friends at the Aquaponics Lab have done an interesting post last week describing the history of the Water Valve.

Lots of people were intrigued on exactly where the water valve is installed and how it’s operated. They’ve asked if we could help to clarify it by showing our FAO based system and how we operate the water valves in here using the Water Elf.

The water flow is simple, water moves by gravity as follows:

Fish Tank ->  3 Grow-beds -> Water Valve -> Sump

Finally from the sump the filtered water is pumped back to the fish tank.

Here is a quick video showing the water flow:


The water valves can be controlled mainly by two ways: A time based strategy or a water level sensor.

For real time accuracy we decided to use a level sensor and we are testing ultra-sonic one. This device uses ultra-sonic sound-waves to measure the distance between the sensor and the water surface. It enables precise adjustments of the ebb-and-flow frequency and the maximum water height inside the grow-bed while giving the ability to easily change whenever desired.

Bellow you can see pictures of the ultra-sonic sensors in our grow-bed:


Ultra-sonic sensor
Ultra-sonic sensor in place (inside the media guard)
Ultra-sonic sensors
Ultra-sonic sensor outside the media guard







Keep informed of our latest developments:







Short on Potassium?

One of the trace elements that aquaponics systems sometimes get short on is potassium, and Paulo thinks that might be why some of the leaves on my cucumber and strawberries are a bit peaky:


Today I’ve started adding 10 grammes of K2SO4 per day — I’ll report back in a week!

A few more pics for reference:

Gareth to the Rescue

Today was valve debugging day:

The flow control valves we’re using are a miracle of upcycling from Paulo Marini, Gareth Coleman and Mike Ratcliffe. They use a bike tyre inner tube and some scavenged parts from blood pressure monitors to do the same job as £200’s worth of metal parts for a mere £20.

We’ve had a couple of glitches with them this week though, and today was the day for sorting them out… It turned out that Bed 3 valve had just popped off its mounting; screwing that one back on did the trick 🙂

Bed 1 was a bit more of a mystery, but after poking about with Gareth’s multimeter for an hour we figured out that the Cat 5 junction box had a loose connection. Easy to fix 🙂

So now the water is flowing again:

Cheers Gareth!

The Humble by Nature Greenhouse

We are just back from a fantastic couple of days with the team at Humble by Nature – lovely aquaponics set up with a side order of Black Solider Flies.  After doing a bit of filming we installed a wifi enabled WaterElf monitoring system in the greenhouse.  The only downside was the sound of the cockerels competing for attention outside our tents at 6am each morning, but it was a small price to pay!

Nitrate Deficiency in Aquaponics

It has been a few months since we started the University of Sheffield aquaponics system and the plants have been developing really well:

Nitrate post 1

Although a closer look reveals something else! Last week one of our team members found out there was a kind of yellowing developing in some of our plants.

Nitrate post 2

We set out to investigate what could be causing it and how we would sort it out.

First we examined the affected plants to look for obvious pests or other diseases and there were none. So it is probably some kind of toxicity or deficiency. As the system is new and toxicities are rare in aquaponics systems we supposed it is a deficiency. The complication is that there are more than a dozen possible nutrients so we need to follow a methodical approach to find out which one(s) are deficient.

The first thing to do to identify the missing nutrient is find out if the more affected leaves are new growth / upper leaves or the old growth / lower leaves. In our case the old growth was more affected.

This means the issue is possibly a mobile nutrient (instead of an immobile nutrient); a mobile nutrient has the ability to move from the old leaves to the new ones to support the plant development therefore the old leaves show the symptoms first. Great! This eliminates almost half of the possible nutrients.

Then the next step to follow is evaluate if:

A- The yellowing is on the entire leaf.

Nitrate post 3

B- The yellowing is more pronounced but the leaf’s veins keep a green look.

Nitrate post 4

Option A is our case.

The final step is defining if the plant has necrotic stop (dead tissue) or not.

Nitrate post 5

As our leaves show no signs of dead spots the most likely nutrient missing is nitrogen / nitrate.

This is a very interesting result:

On one hand this is an expected outcome as we are feeding our system 3 grams of fish feed per metre square per day and the normal range for a media based aquaponics without solid removal is somewhere between 10 grams to 40 grams (the exact quantity will depend in plant growth/light intensity/plant type)

On the other hand the nitrate concentration is 20 ppm (parts per million) using a liquid test (API Fresh Water) and 50 ppm using a dip strip (6 in 1 Tetra test). This range is not necessarily low for aquaponics.

We will test our assumption by increasing the feeding quantities and checking the results in the following weeks.


Three Key Issues with Conventional Farming and How Aquaponics Can Help

Conventional agricultural practices have made it possible for us to provide over seven billion people with food. This is a great achievement, however, there are more than a few problems associated with the current system. Not only does it have direct negative environmental impacts, it is also unsustainable in the long term. Thus, in order to secure the future of  coming generations we must find alternative solutions.

So how does aquaponics come in the picture? Surely, we are not suggesting that we should stop using agricultural land and grow all our food in aquaponic systems. But we do believe that this technology can play an important role in producing more food sustainably, and that together with changes in the way we use land, transport, store and – perhaps most importantly – think of our food, it could help us achieve food security in the future.

So, what’s wrong with conventional farming and how is aquaponics different? Here are my top three reasons why we should come up with a new strategy for producing food and what role aqaponics could play in it.

1. Takes up lots of space

We have already converted around 50% of habitable land on Earth to farmland, which has significantly contributed to the loss of species and natural habitats. In order to meet the increasing demands of a growing population more and more land is being put to food production at the expense of biodiversity. In addition to putting many species in danger, conversion of natural areas like tropical rainforests also speeds up climate change, which in turn poses a threat to agriculture itself. Ironically, since more people will need not only more food but also more living space, this vicious circle will result in competition for land from urbanization and agriculture.

Aquaponics offers a means to producing more food without using up more land by spreading vertically instead, using “spare” urban spaces in and around buildings, or even below ground. As long as light (artificial light is just fine) is available, these systems can function perfectly well anywhere from the edge of a parking lot to a corner in the office on the 10th floor.

2. Inefficient and wasteful

Plants grown in the fields can only take up a portion of water and fertilizers applied. A simple reasons for this is that roots can only access a limited volume of soil and are therefore only able to absorb what is in their immediate surroundings. Although some nutrients are delivered to them by the mass flow of water, a lot will get washed away before they could be absorbed. Many ions, especially phosphates, also get bound to soil particles and become immobile, with the bulk of them remaining out of the plants’ reach. Since plant productivity is positively correlated with nutrient and water availability, in order to maximize yields we dump large amounts of fertilizers on fields and flood them with water. This is unsustainable for several reasons. On the one hand, production of nitrogen fertilizers is costly and consumes lots of energy, mainly from burning fossil fuels (I don’t need to explain why that’s a bad thing, do I?). On the other, phosphorus, the second most important nutrient for plants, is a finite resource: we get it from mining rock phosphates, which are running out at an alarming rate. As regards water use, irrigation messes up with the natural water cycle, threatening drinking water supplies and likely causing unpredictable changes in climate. To make things worse, intensive farming practices also lead to loss of soil productivity and erosion, rendering fields barren and unusable in the long run.

As opposed to conventional farming, aquaponics uses no fertilizer or, as a matter of fact, soil. Instead, plants are grown in a special medium consisting of clay balls infiltrated with water rich in nutrients. These are supplied by bacteria that convert fish waste into nitrates, an ideal source of nitrogen for most plants. This nutrient-rich solution is circulated throughout the system (i.e. fish tank + units containing plants), which means that all of it is freely accessible to the plants. Excessive watering is not necessary either, only the volume taken up by plants and losses due to evaporation need to be replaced. To put it short: no fertilizer, minimal water input, no nutrients wasted and maximum uptake efficiency resulting in high yields. If that wasn’t enough, aquaponic systems are also quite cheap to install and cost close to nothing to maintain, their sole expenses being those of the fish food, some low power water and air pumps, and the occasional bucket of water. Sounds like a fair deal, huh?

3. Polluting

Another issue with agriculture is its huge carbon footprint that results from the burning of fossil fuels for industrial fertilizer production and use in various machinery, not to mention long-distance transport of produce. High CO2 emissions, which contribute to global climate change, are only part of the problem, though. Chemicals applied to fields can get into the environment, polluting rivers and freshwater supplies and damaging natural habitats, poisoning animals or even humans. Pesticides and herbicides can leak into the groundwater and rivers and may eventually end up in the oceans, causing harm to ecosystems far away from the original source. Moreover, in the same way that antibiotics can’t make a difference and also kill “friendly bacteria” in our system, pesticides can often have negative effects on mutualistic fungi and bacteria living in the soil that, under normal circumstances, would help plants acquire nutrients or become more resistant to pathogens and harsh environments. Although fertilizers are not directly toxic, if they get into the environment they can disrupt ecosystems, which may have serious consequences.

In aquaponics a closed system is used, so normally nothing can get out into the environment. For the same reason, it is also unlikely that anything gets into the system, meaning that there is less need for disease and pest control. As mentioned earlier, this technology doesn’t rely on fertilizers and so does not add to the carbon footprint of the industry. Growing vegetables in the city also helps remove CO2 from the air, as well as contribute to lowering emissions from transportation of food (there is no need for it if it’s all grown on your doorstep!).

So, what are we waiting for? Let’s grow a sustainable future with aquaponics!

Aquaponics and self-sufficiency

ReGen Village Netherlands Aquaponics

A number of recent articles (e.g. and have highlighted the efforts of Californian company ReGen to develop a demonstrator village of 100 self-sufficient homes in the Netherlands.  ReGen then plans to build more villages in Sweden, Norway, Germany and Denmark.

ReGen’s self-sufficiency model estimates that a family of three would need 639m2 to live in and provide for all of its water, energy, food and waste processing needs. Given that according to a 2012 survey the average UK home is around 92m2, comparatively 639m2 sounds like quite a lot of space.  However, it includes 120m2 of living space, and can be arranged vertically to reduce the footprint.  ReGen also estimate that the same family of three would need 8,100m2 of land to support themselves using conventional agriculture, making their system nearly 13 times more space efficient.

Of course the interesting aspect for us is that the ReGen model includes 300m2 of Aquaponics to produce fish and plant crops, and a Black Soldier Fly based waste processing system.  Black Soldier Fly grubs are incredibly efficient at eating organic waste, such as waste food and kitchen scraps.  When the grubs have had their fill, what remains is a well-mixed low-odour soil enhancer that can be composted or further processed to produce biogas.  Most importantly however, the grubs themselves provide a high protein food source for the fish in the aquaponics system.  This means that levels of environmentally damaging fishmeal used to produce commercial fish food can be reduced and even eliminated, creating a ‘closed-loop’ system where waste is turned into food and energy. Very neat.

ReGen Village Model 2

This approach is seen as a way to produce more resilient communities that have some protection from climate change with less environmental impact, and to provide a higher quality of life.  ReGen’s goal is to increase political will to make their self-sufficient development model mainstream in the developed and developing world. Of course this is the tricky bit, particularly the UK.  Brexit, our entrenched housebuilding industry, and high land prices are all obstacles.

However, we don’t have to compete with housebuilders for prime development land. Sinus Lynge of EFFEKT architects who helped develop the ReGen model talks about the fact that giving up space to food in inner city areas is “unthinkable”, but is it really?  There are currently some great UK examples of urban farming and aquaponics, such as Growing Underground and GrowUp, that are blazing the trail to demonstrate the scalability and affordability of such urban farms.  What we need is more of them, and fast. Of particular importance is demonstrating the viability of urban aquaponics schemes that have been ‘retrofitted’ into disused or underutilised buildings, on the roofs of occupied buildings, or even underground. Developing such opportunistic urban niches is the way to sway local and national political will, and arguably a more effective way of connecting with more people than the semi-rural villages depicted in ReGen’s images. Perhaps then the next list of proposed ReGen villages might also include city-based projects in the UK.