If there's baby pigs in there - that's exactly how high the coroplast needs to be! Otherwise, it is best to be a good 3 grids down, for good air circulation.
FYI. the "umm" stuff reads very condescending. Imagine saying that. It's like you're treating the poster like an idiot. The grids look to be smaller than the typical C&C grids, but it's better than a pet store cage. Umm....try to be a little nicer, why don't ya.