fruity pebbles with marshmellows

Question

dear rabbi i was going threw your list and i noticed that fruity pebbles are listed kosher for passover. I still cant see why fruity pebbles should be kosher at all for pasover isnt it minhag that we check the rice atleast 3 times even thought there is a slim to none chance of wheat in rice. this is what i have learned in my years of yeshiva. Respectfully Nathan Bailey