Hi Marcel Sorry if my answer seemed a little kurt as it wasn't intended that way. The test kit manufacturers must share a lot of the blame for the confusion. It is relatively easy to measure Alkalinity (A) but not so easy to measure KH. Since A=KH so long as KH<=GH and since this is the case for the vast majority of us aquarists the easy answer is to label the Alkalinity test as KH. In fact my "KH" test kit label also contains the word alkalinity in smaller print. Your case is an example of why I think it's worth knowing the difference.