Wall Fish TankA place to live for your favorite pet

- a select article from the Aquaponics Journal

by Rebecca Nelson

A mini aquaponics system is an excellent means of demonstrating aquaponic principles and the nitrification cycle in a recirculating aquatic environment. Following are instructions for building a small system that is ideal for a teacher, students of hobbyists who wants to get a start in aquaponics.

What You’ll Need:

Following is a list of the parts you’ll need to build an aquaponic system. The next section, Components Explained, describes and explains each of these components and includes recommendations for alternative items and specific products.

* A tank for the fish: 3-20 gallon, glass or plastic container ($5 – $20)

* Gravel – 2.5 lbs./gravel for every 5 gallons of water in the fish tank ($2 – $5)

* Water pump – 3-4 watt pump capable of lifting 18” – 54” at 30 – 100/gal/hour (small circulation or fountain pump is ideal) ($19 – $40)

* 3 ft. of plastic tubing that fits the outlet on your water pump ($1 – $2)

* Aquarium air pump sized for the number of gallons in your fish tank ($8 – $16)

* Air stone (1” – 3”) ($1 – $2)

* 3 ft. of air tubing to connect the air pump to the air stone (must fit the air pump outlet) ($ 1)

* Grow Bed – must sit on top of fish tank and be 3” – 8” deep ($ 5 – $20)

* Growing Medium – enough pea gravel, perlite, coconut coir, expanded clay pebbles or peat moss to fill the grow bed ($2 – $5)

* pH test kit and, depending on the pH of your water, pH down or pH up ($5 – $15)

* Fish and plants

Tools Required:

*

Drill with 1/4” or 3/16” bit and 1/2” bit

* Scissors

* Electrical tape

Component Explanation:

a tank for the fish

The fish tank can be a glass or plexi-glass aquarium or you can use any other clean container that holds water, for example, a plastic tub, bucket or barrel. We recommend anything between 3 – 20 gallons, although, you can go with a larger tank if you have the space. Small, clean plastic amphibian cages, available in most pet shops, make an excellent mini-system. They hold about 3 gallons and are quite inexpensive.

The standard sized fish aquariums of 10 and 20 gallons are also reasonably priced. The larger the tank, the larger grow bed area you can support. As a general rule, you can support 1 – 2 square feet of growing area for every 10 gallons of fish tank water.

gravel for tank bottom

The gravel serves as a home to the nitrifying bacteria that convert ammonia to nitrite and then to nitrate, which can be used by the plants. Most pet stores carry natural or colored aquarium gravel. The individual pebbles are about 1/8” in size. Be sure to wash the gravel thoroughly before using it because it is often dusty. Unwashed gravel will cloud your tank water.

water pump and tubing

A small water pump is used to pump the water from the fish tank to the grow bed. After the water is pumped into the grow bed, it gravity-feeds back to the fish tank. You’ll need enough tubing to go from the outlet on the pump to the top of your grow bed and form a circle within it.

air pump, air stone and tubing

You need an air pump to blow air into the tank water for both the fish and the plants. Tubing connects the air pump to an air stone at the bottom of the tank. The air stone breaks the stream of bubbles coming from the air pump into micro-bubbles, which greatly increase the oxygenation in the water.

grow bed

The grow bed, which sits on top of the tank, must be slightly larger than the length and width of the fish tank. The grow bed is filled with a growing medium that the plants grow in. A plastic Rubbermaid container, a garden planter or other container that will sit on top of the tank will work fine. The container should be between 3” – 8” deep.

You can use a plastic tub or, for a very nice looking unit, build one out of plexi-glass and seal it with a non-toxic, silicone glue. If you build the grow bed, you can accommodate an aquarium light by making a cavity in the grow bed that the light can slide into. If you are using some other kind of container, a light can sit just behind it if there is room.

growing medium

A growing medium is a porous, chemically inert material that holds the plant roots and maintains moisture. Examples include: perlite, expanded clay pebbles, peat moss, pea gravel and coconut coir. You need enough to fill your grow bed.

fish and plants

In an aquaponic system, the fish provide the nutrients the plants need and the plants purify the water by consuming those nutrients.

Optional Components:

aquarium heater (for tropical fish)

Most gardeners or aquarists setting up an aquaponic system choose ornamental fish for the tank and most ornamental fish originate in tropical waters. A tank temperature of 78 degrees F will need to be maintained for tropical fish. Two kinds of aquarium heaters are available, submerged and tank-side mounted. Either will work, but be sure the heater you choose is sized for the number of gallons of water in your fish tank. If the aquaponic system is placed in an area where the air temperature is maintained between 70 – 76 F or, if you choose cool water fish goldfish, you do not need a heater.

light for fish tank

Most aquariums have a florescent light so you can see the fish and monitor their health. You can add one if you’d like but it is not a necessity.

grow light for the plants

If you establish your system in an area with low light levels, you may need to add artificial light for healthy plant growth. Keep in mind that bright light will quickly encourage algae growth in the fish tank. You should try to point an artificial light in a way so that it does not directly penetrate the fish tank. If you do have rapid algae growth, you can scrape the interior walls of the fish tank or buy a plecostomus, a fish that eats algae. If the grow bed is in a windowsill with bright sunlight, in a greenhouse or planted with plants requiring low light levels, a grow light isn’t necessary.

Assembly Instructions:

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Great tips from the Grober Green!