It's so "rocky" that with those liquid test kits it doesn't even register on the GH chart and the same with KH. I think I counted close to 50 drops before it changed color but it's been awhile since I tested it. We have to have a water softener in our house otherwise it does something to the pipes. Before anyone asks I get water directly from our well before it goes through our softener. But if you look at my last post I said it was most likely biofilm or something that just hardened.