If you live in a soft water area, your tap water probably has very little KH and GH. Low KH means pH can swing or crash, and low GH means fewer of the minerals fish and plants need. This calculator tells you how much buffer to add, based on the drop count from your NT Labs test kit.
GH & KH Calculator
What are KH and GH?
KH (carbonate hardness) is your water's buffering capacity, its ability to hold pH steady. Fish and filter bacteria use it up over time, and rain or top-ups with soft water dilute it. GH (general hardness) measures dissolved calcium and magnesium, minerals that fish, plants and filter bacteria need.
What should my KH and GH be?
As a general guide, we aim for 6 drops on the NT Labs test for koi ponds and 3 drops for aquariums. These are generalisations. Fish from different parts of the world need different GH and KH, so check what your species prefers.
Which buffer do I need?
Use KH buffer when your KH test is low and GH buffer when your GH test is low. They are separate products. To test your water, we recommend the NT Labs Aquarium Lab Multi-Test Kit or the NT Labs Pondlab 200 Multi Test Kit, which are the same kit in different boxes.
Can I use this for an aquarium?
Yes. Choose the aquarium target, or enter your own.
