i don't think bulk buying is that good an idea.
1) there's a best b4 date.
2) where are u gonna put it.
3) HOW MANY FISH ARE YOU GONNA FEED?
4) a normal tub tetramin pro flake food will last me 2-3 months and i feed 3 times daily so if u bulk buy then most of the nutrition could have been broken down to nothing after a few months.
It may cost more for small amounts but do you have that mannk tanks and with that manny fish in it.