Introduction: Barrel Aquaponics System for Small Balcony

While there are quite a few ibles and how-tos on building a one barrel aquaponics-system, I decided to write another one for the following reason: while all the guides that I found were a great source of inspiration and got me hooked on the concept of aquaponics, none of them seem to be based on resources available where I live in Europe.

Hence my guide to building an aquaponics-system using a blue barrel and plumbing parts available in a typical EU (in my case Austrian) DIY-store.

I will show you how to build and start your system.

I will not cover basics on aquaponics and the biochemical mechanisms it is based on.

Backbone of this system is a food grade 200 liter blue barrel. This will be divided into a fish tank, and a grow bed.

See the final result in action in this video:

Parts you will need:

- 1 200 liter food grade blue barrel. You want one without an removable cover. I got mine for € 10,-- (our version of craigslist)

- 50 liters of hydroton (LIAFLOR; grow media); € 14,-- at a specialist store for building materials – about half the price at the local DIY/gardening-shop

- 1 aquarium-pump, capable of moving at least 300 liters per hour at a head-height of 100 cm; € 17,--

- 1 manual timer, capable to work with 15-minute intervals; I had mine laying around for years otherwise available for € 7,-- at

- 2 meters of tube, the diameter depending on your pump; € 7,--

- Some zip-ties; € 0,9

- 1 cable clamp (20 – 30mm); € 1,5

- 25 cm of 25mm PVC-pipe (I decided to use “HT-pipe” for all the plumbing, as the there was nothing else available at a reasonable price); € 3,5

- 2 90* PVC angles 25mm diameter; € 6,--

- 1 25 cm 50mm HT-pipe; € 2,9

- 1 50mm end-cap for HT-pipes; € 1,5

- 1 25 cm 80mm HT-pipe; € 2,9

- 1 32mm uniseal for HT-pipesM € 1,9

Additionally you will need: plants, fish, water & a couple of stones for the fish tank.

Tools you will need:
- Jig saw
- Powerdrill
- 5mm drill bit
- 30mm hole-saw bit
- Box cutter (“Stanley”)
- Sand paper
- Sharpie
- Measuring band
- Coarse-meshed sieve

Step 1: Preparing Fish Tank & Grow Bed

Mark the line that will divide your barrel into the fish-tank and the grow-bed using your measuring tape and a sharpie. I decided to cut my barrel into a 27cm (height) grow bed and a 70 cm fish tank. This is the perfect size for 50l of grow media and about 86l of water in the fish tank.

Drill a hole in the barrel at the line you just marked using the 5mm drill bit. This is needed to get the saw blade in, with which you carefully divide the barrel in two pieces.

Depending on the content that was stored in your barrel before you acquired it, you now net to clean your barrel. Mine was used to store corn syrup, so I had to scrub off the sticky remains with lots of hot water and a sturdy brush. When your barrel is clean, mark a whole on the upper end of your future fish tank, you will need this to insert water and access the fish. I cut out a piece of 30x25cm, 8cm from the top of the fish tank. Attention! Measure twice before you cut! The deeper you position the hole or the bigger its size, the smaller the volume of water of your fish tank!

Now sand off any sharp edges of the fish tank and the grow bed. Turn around your grow bed and put it on top of the fish tank. Depending on the type of barrel used, you are now required to fix the two pieces by using zip-ties (see Backyard Aquaponic’s video below on an instruction) or, if you are lucky, the two pieces fit together snuggly without any additional fixation.

Step 2: Installing the Bell-siphon & Pump

This has been the tricky part for me, as I had could not find these fancy plumbing-materials used in the youtube-videos. So instead of using female and male threaded pvc-parts, cut-off valves and bulkhead fittings, I decided to use HT-pipes. That is basically pvc-pipes used for grey water systems, where pieces are connected by simple rubber seals.

You want to start by installing your standpipe (the 25cm piece of 25mm HT-pipe). Therefore we need to cut a hole into your grow bed using your hole-saw bit. I had a 25mm and a 30mm hole saw-bit. In order to find out the optimal diameter, I took a waste piece of PVC (the hole I cut into the fish tank before) and drilled a 25mm hole in. That was too tight to get the pipe through the rubber seal. With the 30mm bit it worked. Now carefully cut a 30mm hole in the bottom of my grow bed, allowing for about 10cm away from the side. Insert the uniseal and your standpipe (with the wider end upwards and the thinner end pointing through into the fish tank). In my case the seal is absolutely tight – no water leakages at all. Now adjust the standpipe to the desired height by pushing and pulling it through the uniseal. This will define the maximum water-level of your grow bed. Now attach the two 90* HT-angles to your standpipe to achieve a S-shaped water outlet.

For the bell, take the 50mm pvc-pipe and insert the end-cap. Also this, sealed by a rubber fitting, should be tight enough for our purposes. Note that all pieces of the siphon and plumbing are held together by rubber seals – if done correctly, no silicone or threaded connections are required to keep your plumbing leakproof!
Obviously, the height of the bell will influence the functioning of your siphon and requires a little planning ahead.

Now cut out the water-inlets at the bottom end of your bell with your box cutter. I also drilled holes into the remaining pieces to increase water-inflow (see picture). Drill some holes into the fish tank and the grow bed where you want to attach the water tube of your pump with zip ties.

Finally attach the tube to your pump, fix it with a cable clamp if required, insert the pump into the fish tank and attach the tube to your tank and bed. Insert water. I put in 80 liters initially.

Now turn on the pump and see if your siphon works. Most likely you will need to finetune it, by adjusting the height of your standpipe in the growbed and by changing the angle of the water outlet in your fish tank. Also the flow-rate of your pump plays an important role. If you bought an adjustable pump – great! This took me about two hours of continuous trial and error. Finalize this step by preparing the media guard: drill lots of 5mm holes into the 80mm HT-pipe.

If you came that far, have yourself a beer!
You have mastered the most difficult parts of the build.

Step 3: Insert Grow Media

If you measured the height of your grow bed correctly, it will hold about 50l of plant media – exactly the size of a bag of hydroton (burned clay pebbles).

You could use pea gravel instead but considering its significantly higher weight and potential PH-issues it could cause, I went for the easily available clay pebbles. Before you insert the hydroton into your grow bed, wash it thoroughly! Otherwise all the dust will be washed into your fish tank. A coarse-meshed sieve is handy for this exercise. I used an old basket of a biycyle I had lying around.

After cleaning the clay pebbles, make sure you put your media guard around your bell siphon. Only then pour your grow media into the grow bed.

Congratulations, you finalized your one barrel aquaponics system! You are now ready to cycle your system and then introduce plants and (finally) fish.

Step 4: Final Result

Finally I would like to show you some videos of the result:

- The balcony system described here in various videos

For further information on the topic find here some of the most valuable resources available online:

- Backyard Aquaponic’s great video on I-Barrel Systems
- Spaceman Spliff’s Instructibel on the topic

If you have questions, please let me know. Thanks for reading and posting your comments!