Mod podge dries pretty fast. Its dry to the touch within an hour or so. I would let it sit overnight. If you did faux rock make sure you do more than 1 coat do like 3-4. I used to use mod podge but the stuff wears down and is noticably affected by the heat after long periods of time. I would look into some poly sealers in the paint section. Minwax sells a clear poly for 9$ that worked great with only 2 coatings.
Thank you. I just need it because I put tile down on my viv instead of what I had and wanted to put some sand on it for traction. I got the washed and filtered play sand for the traction.
After putting mod podge down and sprinkling sand on it, i would do a waterd down coat of modpodge over it too keep the sand from being pulled off. just add a little watter too a bit of modpodge. you really dont need a lot of water.