Aquaponics is a growing technique that takes two efficient systems and combines them to work symbiotically with each other: Aquaculture is the process of farming fish (such as tilapia, koi, or bluegill) or shellfish, while hydroponics is a method of growing plants without soil. When the two are combined, you can create a nearly closed loop system that produces both plants and fish for consumption.

Aquaponic setups are nearly identical to hydroponics, the main difference being the source of the nutrients for the plants. Nutrients are no longer added to a water tank – instead they are produced by waste produced by the fish. The diluted fish waste is pumped out and delivered to the roots of the plants. The roots absorb the nutrients and purify the water before it is returned to the aquarium. Fish food is the only input you’ll need, and this can be grown or purchased for the system.

The primary nutrient produced from the fish waste is nitrogen with trace amounts of other minerals. Because of this, basic aquaponic systems are effective for leafy greens, but if you’re cultivating tomatoes, cannabis, or fruit and vegetables, you’ll need to add additional nutrients like phosphorus and potassium. This is remedied by a double-root zone.

A double-root zone allows you to divide the roots into two sections. The bottom half of the pot will be submerged in the water while the upper half of the pot can be filled with soil. This allows additional nutrients to be applied to the roots without contaminating the water. The two sections can be separated by burlap, which allows the roots to travel through while preventing the soil from reaching the water. When watering with additional nutrients, avoid oversaturating the soil to keep the water in the aquaponics system clean.