The API Liquid GH & KH Hardness Test Kit for Axolotls

What is the API Liquid GH & KH Hardness Test Kit?

The API Liquid GH & KH Hardness Test Kit is an accurate and easy-to-use liquid test kit that measures the general hardness (GH) and carbonate hardness (KH) of your aquarium's water. For axolotls, keeping these levels stable is crucial—it directly impacts their comfort and long-term health.

Axolotls thrive in softer water conditions than many tropical fish, ideally matching the slightly acidic, soft-water environments of their native Mexican habitats. This kit helps you track and maintain those conditions, keeping your axolotl happy and stress-free.

The API Liquid GH & KH Hardness Test Kit is designed for freshwater use only. It comes with two dropper bottles containing the specially formulated GH and KH test solutions, two test tubes, and step-by-step instructions.

What is carbonate hardness (KH)?

Carbonate hardness, also known as alkalinity, is the measure of carbonate and bicarbonate concentrations dissolved in water. For axolotls, KH is particularly important because it stabilises pH. Axolotls prefer a pH between 6.5 and 8, and without adequate KH buffering, your water can swing wildly in pH—something axolotls find genuinely stressful. If your KH drops below 3 °dKH, you're looking at potential rapid pH shifts that can harm your pet.

What is general hardness (GH)?

General hardness is the measure of calcium and magnesium ion concentrations dissolved in water. Axolotls prefer softer water (generally 4-8 °dGH), so knowing your GH helps you understand whether your tap water is suitable straight from the tap or whether you need to adjust it.

Why should I test for KH and GH with an axolotl tank?

Tap water rarely provides the ideal conditions axolotls need. Some supplies have very low KH (below 3 °dKH), which offers virtually no pH buffering—leaving your axolotl vulnerable to stress.

Additionally, when water evaporates from the tank, hardness minerals are left behind. Topping off with tap water simply adds more minerals, causing a steady creep upward in GH. For axolotls, this gradual hardening can shift them away from their preferred soft-water range over time. Regular testing keeps you ahead of these changes and prevents the slow stress that builds when conditions drift.

Testing regularly is the difference between an axolotl that's merely surviving and one that's genuinely thriving.

For instructions about how to use this API Liquid GH & KH Hardness Test Kit, consult the step-by-step instructions provided in the box.