A swimming pool is a major investment that needs continual maintenance not only to retain its value but to be safe to swim in. But if you’re still swinging a long-handled net to skim leaves and scrubbing its walls and floor to remove algae, you owe it to yourself consider investing in a modern pool-cleaning robot that can do that grunt work for you. Robot pool cleaners come in various shapes and sizes, diverse capabilities. And as you might imagine, they come with a wide array of price tags, with the most sophisticated models going for $2,000 or more. Here are our top picks, followed by a buye…