Mine are not attached to the tubs, the weight of the water and diameter of PVC keep them VERY stable.
Nice, I'm going to have to try that... we have some low ceramics that are stable, but they're too big for hatchling tubs, and too small for the larger animals, and we're constantly cleaning up wet newspaper.
The Earth is the cradle of mankind, but one cannot live in the cradle forever. -Konstantin Tsiolkovsky