Guide to Aquaponics – Hydroponics with a Fish Tank


If you watched the movie Snowpiercer then you might have wondered how the train was able to sustain its agricultural output despite the lack of limited resources. Well, part of that could be thanked to aquaponics, which takes hydroponics to a whole new level. This guide will take you through what aquaponics is and what makes it awesome.

What is Aquaponics?

Let’s first start off with what a hydroponic system is. Hydroponics is a method of growing plants in water-based medium. Soil is not needed because the water is supplied with the two core elements, nutrients and oxygen, that plants require to thrive and grow.

For hydroponics to work, however, the water will need to be constantly replenished with oxygen and nutrients in order for the plants to survive and grow. Well, this is when an aquaponic system comes in and becomes a game changer. It’s based on a recycling approach where the plants rely on the fish effluents for nutrients, while the fish relies on the filtering properties of the plants to keep the water clean.

Setting up a system like this might sound scary at first but the good news is that it is totally scalable. It works for a lot of sizes and budgets. For example, an apartment-living individual can set up a small countertop herb-growing system using the aquaponics approach.

How Does Aquaponics Work?

There are actually four common methods of aquaponics that are widely in use today. Which method you pick will depend on many factors including size availability, desired agricultural output, and type of plants you wish to grow.

Deep Water Culture (DWC)

The premise of this method is to suspend the plant roots in a nutrient and oxygen-rich solution. It’s also known as the raft method to some because a popular way to suspend the roots is by securing the plants to a floating Styrofoam raft. The canal or tank where the rafts are placed is connected to a water tank filled with fish. In a typical setup, the oxygenated water from the fish tank will flow down to the plant tank by gravity then flow back into the fish tank again via a water pump.

Media-Based Aquaponics

Media-based systems are most popular with DIY home growers. It’s a similar set up to the deep water culture method, except the plants are growing in a planting media such as clay pebbles and gravel. The planting media supports the root of the plants and also captures the fish effluents before the solution returns back into the fish tank.

Nutrient-Filmed Technique (NFT)

This aquaponics system works best for plants that don’t require much support. NFT utilizes a narrow trough, such as PVC pipe, that’s tilted so that nutrient-rich water can flow through via gravity. At the end of the trough, the water drains back into the fish tank then pushed back into the top of the trough via a water pump.

Vertical Aquaponics

Those who lack space could try the vertical method. There are a variety of setups that could be used. One common method, for example, is to set up vertical pipes where the nutrient-rich solution will trickle down from the top after being pushed upwards by a water pump. You will create small holes along the side the of pipes where the plants will be secured. This works well for leafy greens and other types of plants that don’t require much support.

How is Aquaponics Beneficial?

There are many great benefits to an aquaponics system, especially if you compare it against a traditional hydroponics system. First, a well-maintained aquaponics system will significantly reduce the amount spent on nutrient solutions. Part of the money that would have been spent on fertilizer would go to fish feed instead, which is so much cheaper.

A key feature of aquaponics is about reducing waste. If you are able to create a good balance between the fishes and the plants then there shouldn’t be much for you to take out. For example, one of the biggest frustrations of hydroponics is having to flush out the water periodically to keep the tank clean of harmful build-up.

Common Questions About Aquaponics

Here are some common questions that are asked by people who are new to this gardening approach.

Does Aquaponics Need Sunlight?

Yes, most crops you may want to grow in an aquaponics system will need full sun conditions to grow to their full potential. It, however, isn’t easy to find an indoor space that gets this amount of sunlight. As an alternative to natural sunlight, you could set up some grow lights around the tank. These lights are designed to mimic the wavelengths of natural sunlight.

Do I need to Change Water in Aquaponics?

No, at least not as regularly as a hydroponic system would require. You will most likely need to only change the water in the event of an emergency situation, such as when there’s excess bacteria or sodium in the water. Since it’s an enclosed system, it’s important to monitor the water quality closely to prevent the spread of diseases among the fishes and plants. Water-changing is more likely with smaller aquaponic systems.

How Many Fishes Do You Need for Aquaponics?

This will depend on several factors including the type of system you build, the type of plant you grow, and the size of the system. In general, you should aim to have about 1 pound of fish per five to seven gallons of tank water.