Carbonate Hardness (KH) Test Kit

The Carbonate Hardness Test Kit uses a sulphuric acid drop-count titration to measure the concentration of bicarbonate and carbonate ions, expressed as dKH (degrees of carbonate hardness). KH is the single most important indicator of pH buffering capacity — a low KH means pH is prone to sudden swings, while an adequate KH maintains pH stability between water changes.

Each drop of reagent consumed equals 1 dKH, and the endpoint is a clear colour change from blue to yellow. The test takes under two minutes and provides a direct, quantitative result without colour-matching ambiguity.

KH is consumed by biological processes and CO2 injection in planted tanks, making regular monitoring essential. Marine reef systems target 8–12 dKH; planted tanks often run 3–6 dKH; Rift Lake cichlid tanks are maintained above 10 dKH.