make sure u get blk egg crates - ive read up that white egg crates may releaase phosphates.
I'm curious as to how non-porous plastic can leach. Has this claim been tested? How was the experiment conducted? Were the control and test aquariums empty (except for the egg crate)? Did they use the same source water, same pumps, etc etc?
I would be more inclined to believe that something other the egg crate was responsible.