Mike Wise asks: << Are you living in the Miami, FL area? If so your water is perculating through an > old coral reef. The water is leaching CaCO3 (either limestone (calcite) or the > more soluable form aragonite from the substrate. This raises the KH sky high. >> >> Just for the record, Mike, There are a significant number of "Robert"s in the Boise, ID area. In fact I suspect there is less homogenaity in the genetic pool of white mice than in the name pool of Boiseans. Any way to distinguish one Bob from another is quickly latched onto. I once chased my (now ex-) wife to FL to try once again to salvage my marriage. When I got back to Boise I found myself refered to as "Miami Bob". We get our drinking water from a number of subterranean aquifers. There is very little but igneous rock here. The KH, GH, and pH all vary from season to season based on where the water table lies. There are a number of phosphate mines within a hundred miles of here, so carbonate deposits are also possible, I suppose. There may also be some kind of carbonate compounds in the fertilizers they use on the spuds and sugar beets. The "Snake River Aquifer" is a very large and geologically complex area. I'm going to find some hydrochloric acid and a good test kit for KH. Then I'm going to experiment a little. Bob