I am installing a new A/G. Have had one in the past and helped family members install one also. However, I have never been able to compact sand well enough to maintain smooth bottom for liner installation. Someone told me to mix 7 parts sand to 1 part Portland so that it would compact better. However, will this end up like hard concrete or will it still have some cushion? I'm not a big fan of Gorilla pad or any other cloth type surface. All suggestions welcome.