Several years ago, I was researching greenhouses and growing food year round. While watching some of the seemingly endless number of Youtube videos on the topic, a came across something I had never heard of before, called Aquaponics, and it interested me ever since. It seems like I wasn’t alone, as not very many people are familiar with this method of raising food. Here is a brief overview of what its about, and how it works.

What is Aquaponics? Aquaponics is a method of growing which combines aquaculture (raising fish), and hydroponics (growing plants without soil). Water from a fish tank is cycled to plant grow beds, where beneficial bacteria convert fish waste in the water into food for the plants.

Most people understand the concepts of traditional plant growing, which is planting a seed into the ground, or in a pot of soil, and watering it until the plant matures. This method uses either naturally existing nutrients in the soil, or those that are added, such as from composting, or fertilizer. Aquaponics does not use soil, rather a growing media such has gravel, clay pellets, or even rafts. Wastewater from the fish is pumped into the grow beds, where bacteria convert it to plant food, cleaning the water before it is returned to the fish tank.

How Does Aquaponics Work?

Think of an aquaponic system as a mini ecosystem. Water circulates through the system, providing life for everything in the system, just like any other ecosystem occurring in nature. Some plants and animals use the water, and then it is once again returned to nature to be reused once again.

Aquaponics is a controlled, closed loop ecosystem. The water starts in the fish tank, where the fish use it to survive. When the fish eat, the produce ammonia and solid waste, otherwise known to some as pee and poop. You maybe familiar with having goldfish at home, and know that the water has to be changed out every so often, otherwise the waste will eventually kill the fish. In an aquaponics system though, instead of constantly changing the water, it is pumped (or gravity fed) through a series of piping that runs to the grow beds.

When the ammonia rich water gets to the grow beds, tiny enzymes and beneficial bacteria that build up in the grow media over time, begin their job in the ecosystem, by consuming the ammonia. The bacteria first convert the ammonia into nitrite, then into nitrate. The nitrate is what the plants are able to consume to grow.

Once the ammonia has been filtered out of the water naturally by the beneficial bacteria, it is then safe to return to the fish tank. In some system’s designs, the clean water first will be gravity fed into a separate tank, known as a sump tank. In these designs the sump tank is used to house the sole water pump, which moves the water through the system.

Designing an Aquaponics System

The basic elements to an aquaponics system are the fish tank, and grow beds with media. Other elements can be incorporated into the design with make maintenance easier and operating costs lower. These include items such as air stones, back up power, shut off valves, water heaters, and solids filters. We’re just going to focus on the basics in this section of the article though.

People use different things as fish tanks, but one common container for back yards and smaller green houses are IBC Totes, or Intermediate Bulk Containers. These are pallet mounted sturdy plastic containers with a metal caging for strength, which are traditionally used for transporting bulk liquids and powders. This type of container is popular as a fish tank because they can hold large amounts of water, typically 275 gallons (or 1000 L). They can also be found very cheap, or even free if you luck out.

One thing you’ll need to watch out for when re-purposing containers for aquaponics systems though is what they were originally used for. You will want to make sure that the container was originally used for food, or rated as food grade. If the container originally had some sort of chemical in it, it could leach that chemical into your system, potentially even when you clean it thoroughly.

You can also find potential fish tanks at your local hardware store, or feed and seed. Some of these places sell large plastic containers that could be used as a fish tank, or even some plastic pond liners. There are certainly plenty of options available for purchase online as well. Ultimately, what you decide to go with will depend on how big of a set up you want, and how much you are willing to spend.

Grow beds similarly can be made out of cheap repurposed items. A popular option is buying 55-gallon plastic drums and cutting them in half. One barrel can make 2 grow beds, and you can also find these cheap used. But again here, you will want to check to see what was originally stored in the barrels.

There are several popular types of grow media for grow beds. One of the most popular is clay pebbles, or LECA (Lightweight Expanded Clay Aggregate). Clay pebbles are lightweight, but study enough to support a plant, while also being PH-neutral, non-degradable, and highly porous, which help to maintain oxygen in the water. The main draw back to this type of media however, is that they are also on the pricey side.

Expanded Shale is another popular option. It is silicon-based, and also PH-neutral. It is slightly heavier than clay pebbles, but has many of the same benefits.

Growstones are kiln-fire aggregate made from mixing recycled glass with calcium carbonate. These have all the same benefits as clay and shale, but do have one draw back. Growstones tend to collect organic matter in their pores, so they will have to be cleaned more thoroughly. There is some debate on whether or not they are truly PH-neutral, so you’ll want to test them before using.

Lava rock is another cheaper option. They are lightweight and porous, providing beneficial drainage and aeration. The drawback to this media is that they are jagged in texture, which could be rough on the hands, or even on plant roots.

Gravel is the least expensive option, but has many drawbacks. Gravel is heavier, and denser. Smaller plants may have a harder time growing through it. It also does not retain water, and is less conducive to a healthy environment for beneficial bacteria. You have to be careful using this media, because it can sometimes contain limestone, which will mess up the PH in your system.

What Fish to Use

There are many varieties of fish you can use in your system. Some people choose to use ornamental fish like goldfish or koi, and are perfectly happy with that. One of the benefits of aquaponics though, is being able to also raise fish for food. There are a handful of species of editable fish that do well in aquaponics systems.

Before deciding on what type of fish to use in your system, you will have to consider the climate of your location. The average temperatures, the highest, and the lowest, will determine which breed will do the best in your area. Use this information to compare to which climate the different breeds do well in.

You also will need to take into consideration how big your fish tank is, and how many gallons of water are in your system. A good rule of thumb is about one pound of fish for every 10 gallons of water. This will help you determine how many of each fish your system can handle.

One of the most popular types of fish in aquaponics is Tilapia. Tilapia grows quick, has a great temperament, and are hard to kill. They are also omnivores, so they will eat all sorts of different feed. They do the best in temperatures between 70-80°F, but are fairly adaptable. One benefit to tilapia is that they can survive in harsh water environments, which means they are a great breed for beginners in aquaponics, as you’re learning to care for your system.

Rainbow Trout is another option. This is a great option for colder climates, as they can handle water temperatures of 45-72°F, although the ideal temperature is closer to 60. Unlike tilapia, they do not handle dirty water very well. They prefer well oxygenated water, so it’s best to have additional aeration with trout.

Catfish are another great option. Catfish do best in larger tanks, as they can grow to be pretty long. They do well in environments similar to tilapia (70-80°F), in fact they can even share a tank with tilapia. If the temperature gets below 55 tough, catfish will stop eating.

Jade Perch is another breed that’s becoming popular, but can be difficult to find in some places, as they are native to Australia. These fish do well between 75-80°, and will stop eating below 65.

Carp can do well in temperatures between 73-86°, and stop eating around 63, however they can survive very cold temperatures, even icy conditions. They can also be fairly easy to breed.

Largemouth Bass typically do best between 65-90°, but can also survive in lower temperatures. Largemouth Bass raised in a clean aquaponics environment can actually taste better than adult bass caught in the wild.

Types of Plants that Will Grow in Aquaponics Systems

There are many varieties of common plants that will do well in an aquaponics system. Leafy greens such as lettuce, kale, chards do great, as well as other herbs such as mint, basil, chives, and arugula.

Smaller fruiting plants can also thrive in larger systems, with a well-stocked fish tank. These plants require a little more nutrient to grow well, but it is possible to raise plants such as tomatoes, peppers, cucumbers, beans, peas, and squash. Broccoli, cauliflower, and cabbage can also do well in these larger systems.

The Pro’s and Con’s of Aquaponics

Here is a short list of the pro’s and con’s of operation an aquaponic system

• Pros
  • A secondary production stream (fish harvesting)
  • 90% less water usage that growing in soil
  • 4-10 times larger plants and production
  • Absence of artificial fertilizers
  • Environmentally friendly
  • Harvest times can be cut in half
  • Less pests problems than with soil
  • Ability to control the growing environment
  • Year round production of fish and vegetables when done in a greenhouse
  • Thermal mass of fish tank helps heat greenhouse in winter
• Cons
  • The need to have an electricity source and a back up to run the water pumps
  • Building takes a relatively big initial investment
  • Running a system takes a little more knowledge and skill
  • In some cases additional nutrients will need to be added (such as iron, calcium, or potassium)
  • Additional greenhouse heating may be necessary in some areas
  • Any mechanical failure could lead to serious damages

Related Questions

What size water pump will I need for aquaponics? You will need a pump that can circulate you entire mass of water once every two hours. For example, if your system has 300 gallons, you need a pump that will move 150 gallons per hour.

Can an aquaponics system run off of solar power? Yes, it is possible to easily run the water pumps and air stones for a home aquaponics system off of solar power.

How do you keep the fish warm in the winter? If you live where temperatures get frigid, you can incorporate aquarium heaters in your fish tank, or wood stoves, oil heaters, gas heaters, or electric heaters in your green house to keep the temperature controlled.

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