I've never been able to estimate how much water is enough and how much is too much. The few times I tried, I used too much water. So I go by the published recommendation: an amount of water equal in weight to the Vermiculite. If you weigh the Vermiculite in ounces, then one fluid ounce of water per ounce of Vermiculite. If you use grams, then one milliliter of water per gram of Vermiculite. The hardest part is getting the weight of the Vermiculite. Good luck.