The Cheap Vegetable Gardener

Cheap desktop aquaponics system

10.6 years ago Uncategorized

I wanted to create a fun project with my daughter and a proof of concept for an aquaponics setup to have running in my grow box.  For those of you new to this concept this is growing plants in a soilless environment (much like hydroponics) but instead of paying for expensive nutrients you use naturally occurring bacteria and fish poop to grow plants.

Now there are fish farm kits out there but given most of the parts for this build I had sitting idle in my garage I decided to construct my own.

First after a trip to IKEA I found some plastic tubs just the right size for my grow box.  I got two of the bins and one lid.

This is the basic idea of how this goes together, fish in the bottom plants on top.

Next I took a 1/4 inch drill and made several holes on both the bottom of the top tub and also through the lid.  I also added a few extra hole in the lid to ensure water can drain faster from the lid than the water coming in from above.  I also drilled a big enough to fit some 1/2 in plastic tubing from an old fountain pump I had lying around.

It is a bit hard to see from this picture but I cut the top of a 2 liter bottle off and drilled a hole in the cap just big enough to fit the top of the plastic tubing through.  I then drilled six 1/4 holes and pushed a 6 small pieces of irragaction tubing (pieces of straws could probably work here as well) and positioned them right under the plants roots.

I then filled the top tub 1/3 with aquarium gravel (washed pea gravel would work as well) that I had sitting the the garage and topped the rest with some clay pellets.

Next add some plants and pour water from the top until the tub below is full, start the pump and add a few goldfish and the process begins.

 

As the fish breath, poop, and pee they will produce ammonia (NH₄) this is pretty worthless to the plants but after a few weeks Nitrosomas bacteria will begin converting the ammonia (NH₄) to Nitrates (NO₂) which plants can absorb some of the nitrogen from but not very efficiently.  Finally Nitrospira bacteria will convert the Nitrates (NO₂) to Nitrates (NO₃) which is easily converted by the plants producing some nice vibrant greens with fish poop.

You can even do this whole process without even having fish by simply adding pure ammonia to you water which will create the same natural bacterial processes without having to remember to feed your fish and a small bottle of the stuff only costs a couple dollars on Amazon.