Why is it important to test for carbonate hardness (KH) in aquariums?

First of all I am by no means a chemist and I haven’t studied it in many years. But a small amount of knowledge about how carbonates act in the water is really important when working with low pH environments (or any aquarium for that matter).
In this video I run through how to test kH using the salifert carbonate hardness/alkalinity test kit, the role these ions play in regulating the pH, in the nitrogen cycle and how to adjust the alkalinity of your water!
If you want more information ask in the comments, I did not want to make a long confusing video going into the chemical reactions but I am always keen to chat about it with those interested, you can also message me on Instagram linked on my profile.

[@DylanRenke]

Do you have any thoughts about the nitrogen cycle in very low pH (like 4-6)? I've read that the bacteria responsible for nitrification do not live or do well below 6. Seems like it could be an issue, but the thing is that ammonia is present as ammonium instead at low pH and ammonium is not as dangerous for fish.

[@lorenzospina3174]

I have a question for you , in which way you test parameters in blackwater aquariums?