@ elijahfeathers: Yeah, I know it would be a better choice, but that would mean siliconing the tank divider permanently and I dont want that. Also the sealant would be expensive, and what would I do with the fish while it cures? Just not realistic for me :/ Also, I have black mesh on the other side of the divider to decrease visibility, so I have a backup thing I can stick in there should the plastic fail.
@ Sakura: Yes, it does, if the mesh you are using has holes in it, heated and filtered water gets to the other side just fine. :)