I am going to buy a 1000 gallon pool for my backyard. Do I need a filter? If so, what size?

Most small backyard pools come with a basic filter included with the package. If you don't have a filter and a chlorinating device ( small pools generally have a floating dispenser that utilizes tablets that slowly melt and are removed when the pool is being used) you water will need to be dumped within a week or sooner in very hot weather or it will begin to look like a science project. There are many pool kits for sale this time of year at major retailers in your town or online.

Unless you want to drain and refill the pool every2-3 days, you will need a filter and chlorine to keep the pool clean.

Something like this would work fine for you. http://www.walmart.com/ip/19336119?adid=2222222222...