Aquaponics Mastery
Chapter 13 – Cycling Your Aquaponics System

Cycling is the process of establishing the beneficial bacteria that make aquaponics possible. Until these bacteria are present in sufficient numbers, fish waste cannot be safely converted into plant nutrients.

Many beginners rush this stage because they are excited to add fish and plants. Unfortunately, rushing usually leads to stressed fish, poor water quality and unnecessary losses.

There are two common ways to cycle a system.

Method 1 – Fishless Cycling

This is the safest method for beginners. A source of ammonia is added to the system without any fish present. As ammonia levels rise, beneficial bacteria begin to colonise the grow beds, pipes and other wet surfaces.

Over time:
• Ammonia rises.
• Nitrite begins to appear.
• Ammonia falls as the first bacteria establish.
• Nitrite then falls as the second group of bacteria develops.
• Nitrate steadily increases.

Once ammonia and nitrite consistently test close to zero while nitrate is present, the biological filter is functioning.

Method 2 – Cycling with Fish

Some people cycle using a small number of hardy fish. This requires close monitoring because the fish are exposed to ammonia and nitrite during the cycling process. Feeding should be light and water quality tested frequently. For beginners, fishless cycling is generally the lower-risk approach.

Cycling usually takes between three and six weeks, depending on water temperature and bacterial growth. Warmer water generally speeds up the process, while cooler temperatures slow it down.

During cycling, regularly test:
• Ammonia
• Nitrite
• Nitrate
• pH

Keep a notebook or spreadsheet of your results. Watching the numbers change over time helps you understand what is happening inside the system.