Building a low cost aquaponic garden

Note that everything will depend on the amount of available space you have and the amount of inputs/resources you have at your disposal.  The following is the documentation of a household garden we built as a demonstration project for our One School One Garden (OSOG) program in Xela, Guatemala.   The entire garden, including parts like pumps and grow lights cost around $250.
Initial Questions:
Where to put the garden?  Well it depends on what you’d like to raise, the climate you live in and your electricity constraints.  Things to consider:
1 – Gardens outside must be protected from the elements and as such the materials you use may vary
2 – Temperature – can your fish and plants live at the temperatures?
3 – Availability of sunlight
4 – What type of garden?  We used a floating raft system.
Garden Specs in Guatemala:

Grow bed – 4′ x 2′ x 1′ (volume 60 gallons)
Tank – 3′ x 3′ x 1′ (volume 67 gallons)
Plumbing – 1” PVC
Garden Materials in Guatemala:
1 1” bulkhead adapter
4 feet of rubber tubing to connect pump to filters
12 1” PVC elbows
Waterproof laquer
Silicone
PVC glue
3 1” rubber rings
1” PVC “T”
2 5 gallon buckets
Lots of scotch brite
Hydroponic pots & grow media (gravel for example)
Plastic lining
Grow light
Air pump with air stones – 2.9 PSI
Submersible water pump – 70 GPH
What you’ll need from the states (it was incredibly difficult for me to find these items abroad):
submersible pump
air pump
hydroponic pots
grow lights (if applicable)
water testing kit

Components:

 

Step one – Building the Grow Bed:
Build a wooden grow bed measuring 2′ x 4′ with legs 3′ tall.  Remember that you need your grow bed to be at least 6” taller than the tank so however you want to reach that height is up to you.  For example, in lieu of legs we’ve simply raised our grow bed using part of a preexisting wall and pieces of scrap lumber
With little resources, I outsourced this to a local carpenter but for step-by-step information on building your own check here
I had the carpenter use thick lumber to make sure it could support the weight of the water.
Step two – Protecting the Grow Bed:
With grow bed in hand we needed to apply waterproof laquer since we’re putting this garden outside.  Remove dust, sand it down and then apply coat #1.  Wait 24 hours and then apply second coat.   Use silicone to seal all the seams.

Applying the laquer

 

Step three – Lining the Grow Bed: 
In Oakland we have the luxury of using “liquid liner” but we went with a more simple thick plastic liner that cost about $3.  Line the inside of the grow bed and tighten around the edges.  Be careful not to open any holes in the plastic lining.  Then nail the plastic to the top of the grow bed walls to keep everything in place.
Step four – Protect More!:
Add another plastic lining!
Step five – Drainage:
Drill a hole 1.75” in the bottom the grow bed, 5” from the center line of the bed.  Screw in and glue the bulkhead adapter into the hole.  Make sure this seal is PERFECT because this would be the worst leak to have!  This is where you’ll put in your piece of PVC to serve as the grow bed drain.

Drainage hole in grow bed

Step six – Building the Fish Tank: 
Build your finish tank and repeat steps #2-#4.  Remember that the general rule of thumb is 1:1 for volume of grow bed to volume of fish tank.  Place the submersible pump into the fish tank and connect the rubber tubing that you’ll eventually connect to the input of bucket filter #1.
Step seven – Making Input for Bucket Filter #1:
Drill a 1” hole in the top of one of the buckets.  Slide an 8” piece of 1” PVC through the hole with about two inches protruding from the top and glue around the seam on both sides.
Then glue an elbow piece and a piece of PVC about 6” long to create an “arm”.  This is where you’ll place the rubber tubing coming from the tank pump.  At the bottom of the PVC piece glue a 1” PVC “T” and then two elbows facing in opposite directions.  This is where the water will empty into the bucket filter.

Bucket Filter #1

Step eight – Making Output for Bucket Filter #1: 

Drill a 1” hole in the side of the bucket, about 2” below the top.  Slide an 8” piece of 1” PVC through the hole, leaving about an inch of PVC on the inside of the bucket.  You’ll want to angle the PVC downwards a bit so that water will flow naturally to bucket filter #2.  Glue as you did in Step #7 and then slide the 1” rubber O-ring from the interior side and glue to the seam to strengthen the seal.  This piece will connect to the input of bucket filter #2.

Output from filter #1 to filter #2

Step nine – Filling the bucket filter:

Fill the bucket about 3/4 of the way with untreated scotch brite that you can buy at any grocery store.  This material will filter out the particulates (fish waste, uneaten food, leaves, etc.) from the water.

Using scotche brite as filter material

Step ten – Making Input for Bucket Filter #2: 
Glue a 1” PVC elbow to the end of the output of filter #1.  Drill a 1” hole in the top of the bucket #2 and insert a piece of PVC about 5 inches long, with its halfway point in the hole.  Glue the hole and then using a combination of elbows and random scraps of PVC build a U more or less so that the incoming water spits out at the top of the filter and trickles down the scotch brite.
Step eleven – Creating the return to the grow bed: 
Drill another 1” hole in the side of the bucket, about 2” above the bottom.  Insert a PVC piece into the hole, glue it in place and glue an O-ring.  We used about a 5” piece but the distance you need to travel to return water to the grow bed will determine your length.  Glue an elbow at the end of the return so it drops the water into the grow bed nicely.

Returning the water to the grow bed

Step twelve – Connect and finish the filters: 

Glue the output of bucket #1 to the input of bucket #2.  Then I’d go around and silicone seal all the joints for extra security.  Finally, fill the second bucket with scrotch brite and your filters are good to go!
Step thirteen – Construct Drainage: 
Stick a piece of PVC into the bulkhead adapter within the grow bed – the piece should be about 2”-3” shorter than the top of the grow bed.  No need to glue this piece.
Then glue a piece of 1” PVC into the bottom of the adapter, where it protrudes from the grow bed and create the drainage to your tank.  Note, the design of this part will depend on where you place your tank.  But here’s a picture of what we did:

Drainage from grow bed to the tank

Step fourteen – Create Rafts: 
Measure out styrofoam so that it fits within the grow bed walls with an inch or two of space on each side.  Then cut holes into the styrofoam to fit your hydroponic grow pots – ours are about 2” in diameter.  Note that you will likely have to cut a hole into the styrofoam to let your drain get air.
Fill with water and then start cycling!  Once you fill the tanks you should apply some chemicals you can buy at the pet store to make sure the tap water is safe for the fish.  We are currently cycling with fish and we chose Koi because they’re relatively cheap and hardy fish that can survive in the cold night time temperatures of Xela.

Finished garden in Guatemala.