Backyard Aquaponics in The Netherlands

Over the past couple of months I built an aquaponics installation in my backyard. In this article I will explain what I did and show the results so far.

Why aquaponics

But first I will tell why… Why on earth would anyone put 3 converted industrial tanks in their garden? And what possesses a person to want to raise catfish or trout? I have pretty much surprised everyone I know with my love for aquaponics. Some think I must have gone mad… Therefore I will start with an attempt to explain the why of it all…

These are benefits of aquaponics named on aquaponics.com:

  • Aquaponics utilizes the nutrient rich water from aquaculture that otherwise would have been a waste product or would need to be filtered in a costly manner.
  • Aquaponics eliminates the cost and time involved with mixing traditional hydroponic nutrients.
  • Aquaponics provides a truly organic, natural form of nutrients for the plants.
  • By eliminating the soil in vegetable production, you eliminate all soil borne disease.
  • Aquaponics uses a fraction of the water that traditional field production does because no water is wasted or consumed by weeds.
  • In aquaponics, plant spacing can be very intensive, allowing you to grow more plants in a given space.
  • With high stocking densities in the fish tank, plants will quickly grow and develop in an aquaponic system.
  • In aquaponics there cannot be any pesticides or herbicides used, making the end product healthier and safer.
  • If your climate permits or if you are growing in a greenhouse, you can grow crops in an aquaponic system year-round.

These are benefits for farmers. They are awesome, but I must admit that none of the problems mentioned above are problems I desperately had to solve for myself. I am not a farmer. So what else is cool about aquaponics…?

A lot of aquaponics enthousiasts want to become self sufficient. Love that… But I consider that an optional side effect.

To me there’s just something so incredibly vibrant and alive about aquaponics… The water, the plants, the fish, together they create a certain humming harmony. The entire concept of it simply struck a chord… Maybe because I descend from a long lineage of tinkerers and farmers. Maybe because of my juvenile fantasy of being the aquaponics expert on board of a space ship (like Kess on Voyager).

From Star Trek: Kes on the USS Voyager tending her garden in the cargo bay.

All I know for sure is that I have my own installation now and it makes me happy to walk outside and check on my fish and plants and plan for ways to improve it. (Maybe some automation, other/more fish or plants, extra grow bed, swirl filter… Hmmm…)

What is aquaponics?

By now you might be wondering what aquaponics actually is… If you’re not familiar with it, then please watch this video. It’s a short but excellent explanation.

Video to watch if you don’t know what aquaponics is. It explains it really well!

The type of system they show in the video is really something I could only dream about. It has 4 fish tanks, 1 tanks for settling and one set up as biofilter, a huge grow bed with plants in floating rafts and a big sump tank. If only…

My aquaponics

My own installation is much smaller, I will first explain the theory of it, how I set it up, what I learned doing that and then show some pictures of the real thing.

Overview of the installation

This is a schematic overview of the way I set up my aquaponics installation.

I started with buying 3 second hand food grade IBC-tanks on the Dutch eBay: marktplaats. One of the IBC-’s now serves as a fish tank and the other as grow beds for plants. The grow beds only need to be 30 cm deep, so I only used part of the IBC for that and turned one of the left over halves into a sump tank and placed it beneath a grow bed.

The sump tank stores water and holds the pump that transports water to the fish tank and the grow beds. The water flows back to the sump by the magical force of gravity.

Growbeds and medium

The aquaponics system discussed in the video has one very large grow bed with plants growing in floating rafts. I think this is supercool, because you can quite easily check the condition of your plants roots and harvesting is as easy as picking up your crispy fresh vegetables… Another benefit of this system is that if you take vegetables out, but then change your mind, you can just put them back and they will keep growing. So yeh, wow…

My grow beds do not have floating rafts though, because I do not have the room for a separate biofilter. Instead I use a medium, which basically consists out of lava rocks. The plants live and grow in the medium, just as they would in soil. The use of medium means that my system does not need a separate biofilter, which saves me a lot of space. The grow beds do all the filtering that is needed.

The reason I used lava as medium is because of it’s excellent features for this purpose. It’s porous so it has a very large surface for the beneficial bacteria to live and grow on. Also lava is neutral in the sense that it does not release any minerals into the water. Last but not least: Lava comes from vulcanoes, therefore lava is awesome! Who needs floating rafts when they got lava?!

Lesson 1: The dust will settle

When adding the medium to the grow beds the water flowing through them turned brown and even became a bit foamy. This obviously worried me… Foamy brown water does not look healthy and it is not something a fish would want to live in…

Luckily after a week the dust settled and the bottom of the fishtank became visible again and another week later the water was as clear as if it just came from the tap. The dust is still at the bottom of the sump and fish tank, maybe I will clean it some day, but for now it does not seem to harm the system, so I leave it there.

Drainage of grow beds

Now most people know that if you put plants in water they drown and their roots will rot. This is also true for plants in an aquaponics installation. So in order to prevent this you need to get plenty of air around those roots. This is done by flooding and then draining the grow beds continuously. I created so called bell siphons to do this, this is a system that starts draining the tank when the water reached a certain level. It works all by itself, mechanically, no wires, no nothing, how awesome is that?

Watch this really short video if you want to understand how a bell siphon works.

Lesson 2: Bell siphons need a break

The video shows the water flowing down from the standpipe inside the bell siphon. It just falls, goes vertically down. I now know it does not work like this in the real world.

After some frustrating attempts to get it working I turned to my great friend The Interwebz and found out there is a very simple solution. In order for the bell siphon to create a vacuum the water has to be able to build up a bit below the siphon. This is done by adding a 90 degree bend and a horizontal pipe to the drain as showing in the figure below.

The drain of the grow bed needs a 90 degree bend to break the water flowing out.

Draining the fish tank

The water from the fish tank has to move and be rich in oxygen for the fish to thrive. Therefore most of the water that is pumped up from the sump goes to the fish and is rained into the tank through a pipe with holes.

To make the water flow back to the sump I created a drain that sucks water from the bottom of the fish tank rather than the surface of the water. This way the entire volume of the water inside tank is refreshed continuously and solid waste does not accumulate on the bottom.

The fishtank overflows but the water that is drained comes from the bottom and not the surface of the water.

Lesson 3: Noisy standpipe

This drain made a lot of noise when I first installed it. The gurgling sound was mainly caused by the top of the standpipe sucking air. If I closed the top the sound went away, but it also changed the way the drain worked.

With a closed top a vacuum was able to be built up and the entire tank was emptied into the sump! Obviously this would kill my fish (when added to the system) and it would overflow my sump if I left it like this, so I kept tinkering to find another solution.

In the end the solution was quite easy. I did close the top, but drilled several holes in it to prevent a vacuum. This solved the noisiness. But still it wasn’t entirely right… The water would not drain fast enough. Time for lesson 4.

Lesson 4: Other drains need a break too

The drain of the fish tank was connected with the sump through a pipe with a gentle slope. The tank overflowed into this pipe and the water could flow towards the sump. Or so I thought…

For some funky reason the water would not flow properly, all I saw was a gentle, lazy stream. The drain could not cope with the large amount of water that was constantly poured into the fish tank and it started to overflow. So again some tinkering was required.

I knew the size of the pipes was good, because if I closed the top of the standpipe, in order for a vacuum to build up, it would create a flow equal to what the pump could produce. So the size was ok.

Then I remembered the lesson I learned with the bell siphons and added 2 90 degree bends to the draining pipe leading to the sump. It was just an experiment, but it solved everything. Apparently this drain also needed a break.

Cycling the system

So with the pump and the drains in place and the grow beds filled with medium I started to cycle the system. Cycling is the proces of creating the ecosystem of bacteria, plants and fish. Throughout this process I knew I could expect peaks of toxic ammonia in the water and build up of minerals.

To be on the safe side I added goldfish instead of trout or catfish. Goldfishes are less sensitive than most other fish and (sadly for them) they are also quite cheap and easy to acquire, making them the perfect candidate for the job.

Luckily I had a mature, cold water aquarium in my living room, so I used that as a source of bacteria for my aquaponics. Ever since there’s water and medium in my aquaponics I’ve been cleaning the filter of my aquarium in the fish tank. I am quite convinced that this helped speed up the cycling process.

Cycling is not done overnight though… It might take up to a year for an aquaponics installation such as this to find balance and to become truly robust. And still heat or cold and throw it off again. For now I just keep an eye on my fish and plants to see if they show signs of stress or nutrient deficiencies and try to do what is necessary to increase the systems overall health.

Thank you for reading my blog and please leave any comments or questions below. Enjoy the pictures!

My aquaponics in pictures

In February I had 3 IBC-’s delivered to my home. They are second hand and were used to store coconut oil and syrup by their former owner.
We cut open one tank to turn it into a fish tank, and two others we cut in half to turn them into grow beds.
I cleaned out the oil and syrup and thoroughly rinsed out the soap afterwards.
We checked whether the tanks were watertight. One of the lids dripped a bit, we managed to screw it on more tight.
After installing all the plumbing, including the bell syphons (big pipe with red lid) we added the lava split to serve as grow medium. As you can see all the family helped, haha.
Next we installed the plumbing and added plants. Check out the 90 degree bends that solved my fish tank draining issues. The red valves are superhandy to control the flow of water. Most of it has to go to the fish, the grow beds both need just enough to make the bell siphon work properly.
After a month I added some goldfish. I read somewhere that the fish would feel safer with some floating plants, so I added some of those as well.
Blooming strawberry and zucchini plants. Notice the yellowish leaves, something is not entirely right yet, I still have to figure out what exactly is needed to solve this. Maybe add chelated iron…? Have to look into that.
Two colourful parasols/umbrella’s! They are not just for looks, they help keep the burning sun off my tender young plants and the fish tank, keeping the fishes cool.