I tried using one of the rubber trugs but the sides are bendy and it was not easy for the ducks to get in and out as they like to stand on the rim to do so and it kind of kept collapsing. I use a plastic storage box with brick steps at the moment. Summer will bring bigger better pools for my ducks, but winter is a chore to drain and refill when the grounds is sodden and won't let the water sink in.
