If you cycle (powerhead) a bucket of water with CC in it you will get your KH approx 4-6 and your GH to 5-7 in around 24 hrs.. Though the number seems high, for some reason its not complete. Meaning that KH and GH comprise of other elements some i.e. calcium, magnesium is more in abundance than outers.....Alkalinity is Carbonates which ties into KH (please correct me if I'm wrong). Not sure what the full composite of CC is, but the GH that it puts out is not enough\complete. Depends on what your are raising and what you are trying to achive you may need to use some additives to balance it out. As an example, I was starting a new tank and I thought that my KH and GH was OK using "A LOT" of CC alone (KH 5 GH 7). I was lucky as I started crushing some pond snails, and the shell were really soft. My pond snail shells are harder in my discus tank with a lower KH and GH. I increased\balanced my GH with some additives and withing a week the shells were hard again....also bump my KH up too on purpose. Basically a little investment to save a lot of money and headaches.