Even in my big safe which has a Palusol door seal I keep all documents in good old Ziploc brand bags in various sizes. Everything in our BOBs get put in a Ziploc brand bag, etc. They even make a bag that has 20 gallon volume. I'd put anything paper or other media just as thumb drives, CD's, etc. in a Ziploc then store in a bucket/Stormcase/etc. just for redundancy.