Thursday, 9 July 2015

Make an affordable desktop aquaponic system

Aquaponics is the process of growing plants using water from a stock of fish - crucially the plants act as filter, cleaning the water so it can be returned to the fish.

This creates a self-sustaining cycle with the dirty water from the fish tank feeding the plants and the returned  clean water keeping the fish healthy.

In terms of growing plants, aquaponics is basically just a standard hydroponic system using the waste water from a fish tank as the nutrient solution.

I'd read about aquaponic systems but never really seen one working, so I decided to build one myself.

I wanted to make a small system which could fit on my desk, be cheap and relatively portable incase was needed it for lectures or demonstrations.

The design I came up with was really simple, affordable and quick to make, and involved using two stackable plastic storage containers.
The containers needed to set-up a desktop aquaponics system
Stackable plastic storage containers used to make the
desktop aquaopnics system

The fish would be in the bottom container and the plants, growing in gravel, in the top.

I drilled a hole in the top container and attached some simple plumbers' pipe, which allowed me to adjust the level of the water reservoir in this container.

Gravel was added to the top container to such a depth it was about 2cm above the new outlet pipe.

I put a simple plastic container over the outlet pipe which still allowed water to flow out, but stopped any gravel blocking the outlet or falling down it.

A pump was then used to move a steady stream of water from the bottom container to the top one.

Although the constant trickle of water from the outlet pipe of the top container, may have been enough to oxygenate the water for the fish I added an additional air pump to the bottom container, just in case.

The outlet in the top container of the
desktop aquaponics system
After letting the system settle for a while I bought two goldfish and a pot of basil - a plant which apparently does well in these systems.

I added the fish to the bottom container, rinsed the soil off the basil and planted it in the gravel and that was it.

Altogether the whole aquaponics system has cost around £30 (about $50) and is pretty compact and portable.

The system has now been running for just under four weeks on my desk near a large window and I'm amazed at how successful it's been so far.

The water in the bottom container looks relatively clear, the fish seem healthy and the basil is flourishing.

The ease and success of such an aquaponics system has really got me thinking about the potential of aquaponics, in terms of providing a relatively sustainable source of food and their use in urban farming.

Although I'm still debating whether an aqaupnoics system could be classified as a wetland - I certainly think they need some more research!

Desktop aquaponics system - after set-up 
Desktop aquaponics system - four weeks after set-up. Fish and plants doing well.  

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