Fishless Cycling For Aquaponics

Photo 23-09-2014 12 51 11 pm

Getting started with your aquaponics system is pretty straightforward once you have the know-how. We will be doing a step-by-step guide to setting up a small system soon, but first I thought it would be useful to talk about the science behind getting your system ready for fish and plants.

There are two options for cycling your system, with fish or without. Getting your system ready so that the right bacteria have established to convert the fish waste into plant food is essential before you start any growing, and to make the water safe for the fish. We think fishless cycling is much more straight forward as your are not panicking about levels of ammonia and nitrite shooting up and potentially poisoning the fish in the initial stages. The cycling process usually takes about 3 weeks.

What you are trying to establish is a natural cycle whereby all harmful substances are eradicated:


Without fish, you need a way of simulating their waste products in the system. Household ammonia is perfect for this, as fish waste is ammonia-based. You can get it from most hardware stores or cleaning supply places (I got mine from Robert Dyas). Using this method you can control the amount of ammonia in your system precisely, which is also an advantage over cycling with fish. (Some people use their urine but this is more difficult to control and potentially not that pure).

Things you need for cycling:

  1. Pure household ammonia
  2. Small pipettes for measuring amount of ammonia you dispense
  3. Test kit so you can measure levels of ammonia, nitrite and nitrate in the water, plus the PH levels. This API kit has everything you will need. 

IMPORTANT: Before you start cycling, test your water. Some tap water already has high levels of Nitrate and is not really suitable for Aquaponic systems (in this case you could collect rain water if you live somewhere with unpolluted rain, or as a last resort you might have to start off with water bought from the supermarket – you can buy 5L canisters for relatively cheap). Always let tap water rest for 24 hours so the chlorine added to UK tap water has evaporated. You can also buy Tap Water Safe products from your local pet shop to make your tap water safe. 

Once you have got your ammonia and your test kit just follow these instructions to get going:

  1. Add ammonia to the tank a few ml at a time until you reach a reading of 3-4 ppm.
  2. Record the amount of ammonia that this took (probably around 3-6ml depending on your tank size), and then add that amount every other day until the nitrite appears at about 0.5 ppm.
  3. Once nitrites appear, half the dose of ammonia or just hold off for a while if you are worried about overdosing the tank, the nitrites will probably increase for a while, do not worry about this, it is normal (mine spiked at 4ppm).
  4. Once nitrates appear at around 10 ppm, and the nitrites have dropped to zero, you can introduce your fish. Mine nitrates went a lot higher than this initally, but up to around 40 ppm is still safe for fish and this number should drop once you plants start to take up nutrients.

WARNING: Be careful with the amount of ammonia you are adding. If you are setting up a small home system DO NOT overdose the system! If this happens you will have to wash everything out and start again which is very frustrating!

This is a graph of what happened in my system, with the PH, Ammonia and Nitrites. As you can see if took a while to settle down and was quite up and down in the beginning:

Screen Shot 2015-02-01 at 19.21.45

NOTE: Your PH should stabilise over time, mine was very up and down but eventually stabilised at about 6.8. This is a good level for both fish and plants.

TIP: It is a good idea to start your seedlings off in the media you are planning to use so you can put them straight in the system once the fish are in. So start the seedlings about a week after you start cycling if you can, a heated seed bed and lots of light helps them to stay healthy. 

Below is a graph of my system also showing what happened to the Nitrates just for interest. My tap water started with around 40 ppm so this is probably not representative of what would happen in most peoples systems but thought I would include it for interest. As you can see the Nitrate increased, and then the point at which it starts to decrease is after I installed some plants.

Screen Shot 2015-02-01 at 19.36.50Happy Cycling!


12 thoughts on “Fishless Cycling For Aquaponics

  1. Save Green Team says:

    We have been doing aqauponics for over two years and I prefer using fish to cycle. Everytime we have set up a new system, we start with about 50 goldfish. They are extremely cheap locally, about 15 cents each. Usually about 1/2 die off through the cycle, but leaving them in the water a few days will add to the ammonia levels. I check the water at two weeks and most of the time between two and three weeks my tanks are ready to add our tilapia. I am sure there are pro’s and cons to both ways, but fish cycling works well for us. I look forward to your future posts.


    • alicejanewoods says:

      Hi thanks for your thoughts! It would be quite expensive to buy that many Goldfish here, and also we don’t much like the thought of so many perishing in the process!


  2. alicejanewoods says:

    Reblogged this on AW and commented:

    Hi all,
    I am in the beginning stages of a collaborative project looking at aquaponics systems as a departure point for artistic interventions. Head over the the new blog if you are interested and to stay updated with forthcoming events and publications.


  3. khanderao says:

    dear sir,
    as we do not eat fish we shall be glad to fishless aquaponics system. adding liqure amonia is more it possible without fish ?


    • alicejanewoods says:

      you can but be very careful about the amounts you add! do not overdose on ammonia! Also remember you can still keep fish and just not eat them but give them a long and happy life 🙂


  4. Rutvik says:

    I want to start aquaponics in small scale can u please give me link where i can get help in understanding whole procedure i know the basics but then also from the beginning want to know the things we should take care of while operating this system


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