I just did the same (invisible floor). I also put compositing tags on the chunks and turned the anti-aliasing up on just those, that seems to help tremendously! I think a combination of the two should solve the problem. As for the stray bouncing pieces.. I am aware of them. Just kind of ignoring them.. The big thing was to make the flicker stop, I will deal with the bouncing pieces as they come. Thank you all for your help and input!