When I watched them build the cross for the church tank out of cheap pressboard I wasn't too impressed - couldn't they have used synthetic lumber or at least marine plywood? The fact that the ugly-as-sin piece of junk wouldn't sink makes them look ignorant and incompetent. I won't be tuning in again any time soon...
I knew from the start thier was air in it, especially if you add objects like shells and plastic decorations upside down into the tanks. I'm pretty sure they knew what they were doing...but for it's just TV and thats it...it was made to give the viewers the thought of "Oh Know, what will they do"....just to keep viewrs on thier toes and interested to stay tune. Remember it is heavily heavily edited and scripted.....if you have not yet, you should view the link posted by zoodiver from above....Brett even explains its mainly for the non-hobbist....and he even relates it to shows featured on animal planet like river monsters and whale wars.