Tabletop Aquaponic System, $50

On the morning of my most recent birthday, I sat up in bed, yawned, and rubbed the sleep out of my eyes.  I walked out to the patio with a cup of coffee, and lo and behold, a $50 bill had sprouted on my money tree.

"How far can I stretch $50?" I asked, and decided I'd challenge myself to build a thrifty home aquaponic system.

What is an aquaponic system?

Plants are grown hydroponically without soil.  Instead of adding fertilizer for the plants, fish live in the water reservoir for the plants.  Through the power of the nitrogen cycle, when fish go to the bathroom they supply nutrients for the plants.  In return, the plants keep the water clean for the fish.

Some benefits of aquaponic gardening include

• Increased access to fresh veggies and herbs year-round.
• In larger systems, edible fish like tilapia and catfish can be grown.
• Can be easier to maintain than strictly hydroponic systems, aquariums, or aquaculture where fish are grown to eat.
• Vegetables, herbs, and fish can be sold for $$$.
• Can be used in a classroom setting to teach about cycles of matter, communities, mutualism, and more.

To build a bare-bones home aquaponic system, I'd need

• A fish tank -- 10 gal aquarium, $12.97 from Wal-Mart
• Something for the plants to grow in
• 2 foot section of 4 inch PVC pipe, $7.18 from Home Depot
• 2 4-inch PVC endcaps, $4.86
• A pump to push water from the fish tank up to the plants,
• 30-45 gal/hr fountain pump, $16.98 Lowes
• 3 feet of 3/8 inch vinyl tubing, $0.99 Lowes
• An air pump to inject oxygen into the water,
• 5-15 gal air pump, $6.77 Wal-Mart
• 1 air stone, $0.99 Petsmart
• Connective tubing, $1.72 Wal-Mart
• Aquarium gravel - $3.74 Wal-Mart
• Plants -- grown free from rooted cuttings
• Fish -- a handful of feeder goldfish cost about $1.00 Petsmart

Some other tools that I thought may come in handy included:

• A drill, 1/8-inch and 1/16-inch drill bits
• Caulk and caulk gun
• A hacksaw

Putting the pieces together

It's a good idea to start with feeder fish

My first step was to fill the aquarium with water and put in the air pump.  The water needed to sit out at least 24 hours to allow chlorine from the tap water to evaporate before it was safe for the fish to live in. After a day passed, I added the fishies.

Cut a channel

With the fish in place, the next step was to give the plants some room to grow.  I started out by using a hacksaw to cut a 2-inch section of the 4-inch PVC pipe.  This step takes some patience, but I promise it's possible to finish.  The open section becomes the top of the pipe that the plants will sit in.

Next, I flipped over the PVC pipe and drilled 4 holes on the bottom to one side.  The fourth hole that's closest to the end of the pipe was drilled with the larger 1/16-inch bit, and the other holes were drilled with the smaller 1/8-inch bit.  I recommend starting with only two or three holes and adding more if needed rather than drilling several and having to plug them up when the plants get too dry down the road.

Drill drainage holes

With the channel cut and the holes drilled, it was time to add the end caps.  Although an employee at Lowes assured me that no caulk would be necessary for this part, it is.  I added a line of caulk along the edge of the PVC pipe, then popped the end caps on.  

Once the caulk had dried overnight, it was time to start pumping water.  Set the channel on top of the aquarium and partially fill with gravel.  Submerge the fountain pump and run the vinyl tubing up into the channel.  Secure the tubing with gravel inside of the channel.

I added plants, turned on the fountain pump, and the aquaponic system was complete!

The system has been running successfully for 3 weeks now.  I did lose some fishies, but I've also been able to add a couple fancier fish now that the cycling is complete.

The system continues to run
smoothly after 2 months

Helpful hints:

• A note about the fish:  It's a good idea to start off with just a few inexpensive feeder fish that are available at just about any pet store.  Don't get too attached to these fishies, because they're probably going to die of ammonia toxicity.  To speed up cycling, leave a clean sponge in an established aquarium for a few days.  Add the sponge to your tank when you add the fish.  This will transfer some of the beneficial bacteria needed for cycling to your system.  To learn more about ammonia toxicity, nutrient cycling, and other options to this process, check out the Aquaponic Source's cycling page.
• Another note about fish: Although comet feeder goldfish are great to kick start cycling, I've learned that they aren't great long term residents for this particular system.  Comet goldfish have a habit of jumping out of tanks that don't have a lid.  There are slightly more expensive fantail goldfish that have shorter bodies and are less likely to be able to build up the momentum required to jump out of the tank.  I wouldn't recommend black moor goldfish because they are likely to experience fungus problems.  Fish fungus illnesses should be treated with aquarium salt that can stress out your plants.
• A note about worms: Red wiggler worms can be added to the gravel to help break down fish waste.  Worms release nutrients for the plants to use and help keep the system clean for the fish.
• A note about PVC:  Be sure to remove all the little shavings left over from sawing and drilling.  If there are any left, they'll get into the water and the fish will eat them.
• A note about gravel:  Be sure to use aquarium gravel and not just any old rocks you happen across.  Rocks that contain limestone or seashells can raise pH to dangerous levels for both the fish and the plants.  Check out the Aquaponic Source for a simple test to determine if your gravel contains limestone.  Another good medium for the grow-bed is Hydroton clay pebbles.
• A note about the fountain pump: The model of pump that I selected was small and inexpensive, but it does not have a filter that protects the pump from getting clogged by fish waste.  For the first month or so, I removed the filter weekly and rinsed the intake in a sink.  Although that was effective, I scratched together a couple dollars for some filter foam.  Using scissors, I cut out a square and placed it under the fountain pump intake.  The filter foam should be removed and rinsed every month or so.
• A note about light: My system ran fine for over a month with just the ambient lighting in my apartment, but I grew tired of leaving my office overhead light on all day.  I sprung for a small desk lamp and fitted it with a 10 watt fluorescent aquarium bulb.  The lamp is plugged into a timer that turns the light on at 7:00 a.m. and off at 8:00 p.m.



Side view of the system after 2 months

For updated information on my bare-bones, home aquaponic system, check out my profile at the Aquaponic Source.

To see more photos of my home aquaponic system, check out my photobucket story.

If you have any questions, comments, ideas, or suggestions, I love to get email!

A special thanks to my Dad for giving me an opportunity to do such a neat project on my birthday!

My system continues to run smoothly after 2 months.