You would have to be careful using chicken Grit because some of it is made from oyster shells.
As for granite grit I don't guess it would be any different(parameter wise) than using granite slabs in the aquarium. My concern would be how sharp the tiny grit pieces are.
there is fine and medium size. The fine is a little bigger then sand and the medium is about gravel size. Neither has sharp edges. I was thinking of getting the fine size for a smother substrate. I was also careful to make sure that it is granite only, no coral.
I did notice that it was l a little sharper then I'd like and that is one of the reason's I'm sending it back (color is the other) for the Granite Grit that I requested. I think the Cherry stone would be fine for some tanks but not for what I'm going for with my 55gal. The Granite grit is more round and not sharp.