I use a 0.8:1 ratio by weight. First, I put the incubation container on a scale and then tare it (zero it out). Then I add 1 oz. of vermiculite. Then I use a water sprayer and wet it until the scale reads 1.8 oz. (1 oz of vermiculite and .8 oz of water). If you use 2 oz of vermiculite, you would add 1.6 oz water.