Hard acrylic plastic air-tights are fine.
Because their diameter and thickness may vary between the various products, you most probably will be forced to store them loose, in a lockable box.
I have seen album pages with 2 1/2" x 2 1/2" pockets, but they were made from soft clear PVC which is frowned on for high quality storage purposes. Perhaps non PVC album pages may be available from your LCS.