Fishless Cycling

pH, nitrate, nitrite test kits in fishless cycling

Fishless Cycling

Fishless Cycling

October 07, 2021

What is it? How does it work? Why should you consider fishless cycling? Let’s look at this popular practice that most farmers use when setting up a new aquaponic system.

What is fishless cycling?

Once you have set up your system and you are ready to start growing it’s important to make sure you have established bacterial colonies in your biofilter before any fish are introduced into your system.

As you learnt in our blog post, “The Chemistry behind Aquaponics, ammonia is converted into nitrates by nitrifying bacteria. In a new system, you need to encourage bacterial growth before adding your fish because we promise you that there are no beneficial bacteria currently sitting in your biofilter. If your system does not have enough nitrifying bacteria to convert your fish waste, the ammonia levels will become too toxic for the fish and you could have some belly ups in your tank.

Therefore, fishless cycling is a method to establish your biofiltration without fish in your system. This process is carried out by adding a different source of ammonia to your fishless system and letting the system cycle.

What are the advantages of fishless cycling?

  1. No accidental killing of your fish, always a bonus!
  2. Establish your ‘good’ bacteria in your biofilter within 10 – 21 days. Which is almost x2 faster than if you were to use fish from the get-go.
  3. You are in full control of your ammonia levels every step of the way.
Empty DWC during the Fishless Cycling Stage

How to conduct a fishless cycle

  1. Add some ammonia to your fish tank until you reach a reading between 2 and 4ppm. Make sure you use pure ammonia without any additives, perfumes or soaps. There are different types of ammonia available:
    • Liquid ammonia like clear ammonia, pure ammonia or pure ammonia hydroxide.
    • Crystalized ammonia in the form of ammonium chloride.
  2. Let your system run its cycles.
  3. Test for ammonia, nitrites and pH daily and record the figures.
  4. Adjust your pH. Try returning it to a good level between 6.8 and 7.2. This is crucial if you have already planted your system.
  5. Make sure you maintain your ammonia levels between 2 – 4 ppm. If it drops below make sure you add more ammonia.
  6. Once you see a constant increase in your nitrites you can start testing and recording your nitrate levels.
  7. Now you wait for that sweet spot!
  8. As soon as your ammonia and nitrite levels reach 0 in your system you have completed your cycle and you are ready to add your fish!

More about the sweet spot in Fishless Cycling

The aim of fishless cycling is to ensure your biofilter can withstand the ammonia levels that your fish will produce once added to your system and ultimately convert the ammonia into nitrates for your plants.

So, when you see the formation of nitrates and your nitrite and ammonia levels start dropping, you know that your system has established some ‘good’ nitrifying bacteria. Once your ammonia and nitrite levels drop to zero then you can confidently say that your biofilter is housing enough ‘good’ bacteria and that they are doing their job. At this point, it is safe to add the fish and hopefully, you have saved yourself a lot of time and a few lives by fishless cycling your system beforehand.

Graph Showing the Sweet Spot In Fishless Cycling in Aquaponics

Now you have a fully cycled system and you can add your fish knowing that your Biofilter has an established bacterial community to carry out the steps in the nitrogen cycle. If you are in need of any test kits, make sure to check out our online shop! We have everything you’ll need to fishless cycle your system.

Happy cycling!