As a beginner in installing wet beds, what products can i purchase at HD(if any) to make the correct mixture and what should the ratio be. A Rep. from A well known maker of cement products told me to just use their sand topping mix w/ a little water . Is this a workable product or should i mix sand w/ another product(eg. dry cement mix ) I saw a crew of tile workers mixing sand and something else together to make a wet bed but the bags were not marked and i did not get a chance to ask them what they were. A definitive answer would be greatly appreciated. Thanks for the help!