You can leave it in the same vial, Test Suspension would seperate and crystalize quit often so you get used to gear doing that.. you can leave it in the same vial as long as the crytals disolve and reconstitute.. and yes, mrplunkey is correct insert a spair needle into the vial to releive pressure.. I have always been overly causious in moving gear to steril vial after seperation, as i would filter it to ensure no contaminates where in my gear.. you will fine either way..