nah, half of that was just to give you a hard time, ray. i don't think enough people on ob do that!!
but the main variable i was considering which i was hoping you would address was shape of the media particles. also, there are different types of packing peanuts, and while we have common access to some, i think others may not. ok, grodan is probly pretty consistent from place to place. but certainly particle shape and size will affect water retention. which is why i suggested an individual particle trial. also, the compaction which you mentioned, as well as i was thinking in your description you had a basically flat layer of foam at the bottom which seemd to me would certainly cause more water to build up due to slower drainage.
the angle of which you drain water from the container was brought up in this thread by somebody else, and that is something which would need to be controlled at the least. it stood out to me because i have always done that with all of my houseplants (and now do with orchids), and it always amazes me how much extra water comes out just by tipping the pot slightly.
plus, i have spent the past two weeks scrutinizing student independent investigation reports for flaws in the scientific method, so i was still in work mode when i read your post. aaaannnd, i really really really hate tv science for presenting limited evidence but stating a matter of fact conclusion as if the matter is closed.
it never is in science...amiright?? anyways, just throwing stuff out there that i was thinking of when reading your results report.