i could see it stopping the ash from going thru to your water, but its not going to "filter" smoke at all.
haha it wouldnt kill you but rice doesnt have the same surface area that activated carbon does. You already have the expensive part in the filter so you should go to wal-mart or a local fish store and get some carbon. API has the best activated carbon, its in larger chunks instead of tiny flakes so handling it makes zero mess and it has way less carbon dust in it than other brands I have used.