S1·E9 Holiday

What could possibly have possessed Yuki to make her charge into the club room brandishing a deck brush and shouting about cleaning up? The brilliant idea to turn the rooftop lake (a.k.a the water storage tank) into a pool for the day! The girls carefully transfer the lake's fish to buckets, scrub out the algae and pond scum, and let their troubles slip away for the day as they enjoy their new pool.