that depends. if you cut them, you can stretch 'em lengthwise. this would take about half the amount needed if you don't cut them.
back to the octo escape. the octo tank at aquatopia has a feeding hatch. there is a lock on it, but some genius placed that on the inside so it is never locked. still flubber never managed to climb out.
the hatch is about 20 cm above waterlevel and I think that with no grip for his suckers flubber just can't open it. if he somehow could get grip on the surface, we'd probably already found him on the floor somewhere.
of course this is theory. if he is persistent enough, maybe he'll prove me wrong some day. hope he doesn't
Well, sometimes it works and sometimes it doesn't. You have to have a lot of velcro (or artificial turf) to make sure that the octo can't reach above it when fully grown. For a bimac, this might be as much as two feet above the water. There are some other considerations too, discussed in past posts. In the end, you have to lock down your tank!