I placed my webcam next to my tank and had it snap a image every 15 seconds. You can clearly see the sponge kind of breathing by getting bigger and smaller. I'm working on another video that I'll have up tonight that is going to be 1 image every 20 seconds to speed things up a bit.
http://www.youtube.com/v/FOPmajzM8IM
http://www.youtube.com/v/FOPmajzM8IM