We’re checking the KH level of the tank behind me and the reason why you check your KH is because the KH controls what your pH level is in your aquarium. If you ever have a problem where you’ve gone away in holidays and you come back and all your fish are dead, it normally means that pH level has dropped away and the reason for that is because the lack of carbonate hardness in the water. I’ve got one sample we have from the tank behind me. If you put one drop of the liquid in the vial with 5ml of water and shake, you can see the liquid is yellow or clear tap colour. Ideally what we want to happen is we want that to go blue and stay blue for at least three or four drops. When the water test comes up yellow or clear, it means the carbon hardness is on zero, which means the pH is very unstable.
I’ve put the carbon hardness increaser in the tank so let’s check whether the solution goes blue instead of staying yellow. Put five ml of water into the vial then add one drop. Before we put that drop in, it was yellow. Now, if you can see that it’s blue, which means the carbon hardness is a lot better than what it was before, meaning the pH is more stable. Another drop. Shake it up. Still blue. Third drop. Four and five drops, still blue.
Six, seven drops and you can see the top of the water is starting to change yellow. It’s changing yellow now, so if the seventh drop turns the liquid from blue to yellow that means its seven German degrees, which means your pH is very, very stable, absolutely nearly impossible for your pH to drop. For a tropical tank, it’s probably better off around four drops before it turns blue. This aquarium having a high KH would be perfect for fish such as African Cichlids.