I'm curious about this too, as I'm having practically the same problem as you. My tap water has a pH of 7.0, with a kH of 3 degrees. The pH in the tank is 6.2, with a nonexistent kH as far as I can tell. I even tried doubling the kit to 10 ml, and it would appear I don't even have .5 kH. I understand why the pH is lower in the tank, because I'm using Malaysian driftwood and ADA Aquasoil, which are both supposed to lower the pH. I wanted this effect because I want to keep cardinal tetras and a few other Amazonian fish. But, I'm concerned about the apparent lack of kH. I'm using a Hagen Natural Plant system for CO2. So far, it hasn't effected the pH at all, and the kH is still nonexistent. I'd like to know if I should be concerned, or what I should do about this problem. I thought about adding baking soda to raise the kH, but I've heard that won't effect the CO2 levels at all. It looks like we both need some advice on this.