You put in whatever amount of water you want to have the concentration be what you want. Usually, you put 1cc in a 10iu powder bottle so each .1cc has 1IU of GH. That makes it easy to use the 1cc insulin syringes for measuring and administration. I wouldn't use something else or get all fancy, just use the bacteriostatic water that comes with kit. They give you the right amount in the kit for all the powder they give you.