How to cycle an aquarium?

3rd May 2023

Cycling a tank is the process of getting your aquarium ready for your fish by establishing a healthy environment with beneficial bacteria. This will stabilise the Nitrogen Cycle. Here's a step-by-step guide on how to cycle a new tank.

  1. Set up your tank: Get your aquarium sorted with a filter, heater (for tropical fish), substrate, and decorations. Fill it with water, and then turn on the filter and heater. Make sure the water temp is steady, ideally between 24-27°C for tropical fish.
  2. Dechlorinate the water: Add water conditioner to neutralise chlorine and chloramines, which can be harmful to fish and bacteria.
  3. Add a source of ammonia: The beneficial bacteria need ammonia to grow. There are two methods:
    a. Fishless cycling(we recommend this as it's more humane): Add pure ammonia or ammonium chloride, or use fish food that'll decompose and produce ammonia.
    b. Fish-in cycling: Add a few hardy fish that can handle a bit of ammonia and nitrite. Be ready to do more water changes to keep the fish safe.
  4. Test the water: Regularly test the water for ammonia, nitrite, and nitrate levels using an aquarium test kit. At first, you'll see a rise in ammonia, followed by a rise in nitrite. Eventually, both ammonia and nitrite will drop, and you'll start to see nitrates. We recommend you purchasing the API Freshwater Master Test Kit.
  5. Keep an eye on things: Monitor the water parameters. If ammonia or nitrite levels get too high during fish-in cycling, do a water change to protect your fish. Continue to add ammonia during fishless cycling to feed the growing bacteria colonies.
  6. Cycle's done: The cycle is complete when both ammonia and nitrite levels consistently read 0 ppm, and you can detect nitrates. This process can take anywhere from 4-6 weeks, sometimes longer.
  7. Add fish gradually: Once your tank is cycled, slowly introduce new fish to prevent sudden changes in water parameters. Add a few fish at a time, waiting at least a week between new additions.
  8. To help speed up this process you can add some bottled bacteria such as the Ultra Bioguard.

By cycling your tank properly, you create a stable and healthy environment for your fish. Remember to be patient and keep a close eye on the water parameters to ensure success.

TL;DR: Aquarium cycling is the process of establishing a healthy environment for your fish by letting beneficial bacteria grow to stabilise the Nitrogen Cycle. Simply put, set up your tank, dechlorinate the water, add ammonia, test and monitor the water levels, and when ammonia and nitrite drop to 0 ppm with nitrates present, the cycle is complete. Then you can gradually introduce your fish. This process usually takes 4-6 weeks. Patience is key!