yeah, the holes all over are important - not only for flow, but also for the hermits to get back out. I drilled holes, but only around the bottom - came out to the tank and saw 10 hermits all stuck in the tupperwear, and not able to climb all the way out. so I then drilled more holes around the top - thus the crabs can climb all the way out now. but yeah, the glue doesn't work too well. I put rubble all over the bottom of the tupperwear - so if it moves, it will just move to another rock.