I use a relatively small and low masonry/cement mixing tub (70 or 80 litres) and fill it with 50 litres of water. It's a bit less water to carry than a kiddie pool and it's sturdy and easy to tip. I change the water every or every other day.
I don't think you can keep a 220 litre pool even remotely clean unless you install a giant pond filter. And no matter what you add to the water it would be no match against the massive amount of goose poop it would collect in no time at all.
I also have a small pond for my two geese. It's about 3.000 litres, and I have a koi pond pump running all year plus usually a filter during the summer. It has tubs with sturdy plants and waterweeds, and all that combined keeps the water pretty fresh. It doesn't always look very appetizing; lots of algaes during summer, but salamanders and dragonflies breed there every year. The geese use it mainly for swimming; they prefer the tub for bathing.