Hello - I'm not a new pool owner, but just recently started getting serious about taking (proper) care of my pool. I have a free form, in-ground pool. I really don't know what the gallonage is. End to end it's 35 feet, average width is about 18 feet. Diving board on the deep end. My best guess is somewhere around 20K gallons. Anyway, this looked like a good place to get acquainted and learn how to take good care of it. Haven't read much of it yet, but I plan on digging into the Pool School. This is a great site, I'm glad I found it! See ya 'round the pool side!