When you purchase a new aquarium you can not immediately put fish into it. To do so will induce a protracted and cruel death for any livestock. Instead, you have to cycle your tank, which involves ensuring your aquarium is full of beneficial bacteria which can break down ammonia/NH3 (from fish poo, uneaten food and other detritus) into nitrite/NO2. Subsequently, other beneficial bacteria can break nitrite down to nitrate/NO3 which isn’t as toxic to fish as the previous two chemicals and can be taken up by plants. This near-virtuous circle (you’ll probably still have to do water changes to dilute the nitrate build-up) is known as the nitrogen cycle. But to get it up and running takes some patience – up to a month.
I use an aquarium test kit to track the water parameters of my aquarium. The test kit is from NT Labs and tests for the aforementioned chemicals that make up the nitrogen cycle as well as pH, Carbonate Hardness/KH, and General Hardness/GH.
Living in Glasgow, Scotland means my tap water is very, very soft, with zero KH and GH. Thus, to provide some buffering in pH swings, I have to add a KH booster (from Arka), and do so up to a value of 3 or 4.
Below you can see a graph of these water parameters, and from mid-October 2025 through to November you can see the nitrogen cycle running its course.
Imbed with custom width & height + Scrolling enabled
