Tony it sets in like 30 mins and then a full cure is about an hour I believe. But just test it, if you can still feel is squishy let sit. MAKE SURE YOU USE GLOVES !!! This crap is sticky as hell and dosen't come off your hands, I learned the hard way. I didn't fill the tank up right away so I can't give you a time frame on that. I just did the backround and then waited liek a week or so while i was getting stuff ready for it. Also when you spray it do it at an angle and leave room for expation. And when your applying it try and like drag it almost, I just did layers and it looked like dog crap literaly but you can't tell now b/c of the live rock. I hope it owrks out for you I love it and I have somem coraline already growing on it !!! yeah !!!! I try an get some shots tonight