I'd go with 30. Any you have left over will get used in daily maintenance before it goes bad. You've got a BIG pool.
edit: I forgot to mention I found the missing polaris 280 at the bottom of the pool when I got the cover off. It's pretty nasty and has a broken wheel. Before I replace the wheel, can I clean it up and hook it up and make sure everything else is working? I don't want to replace a bunch of parts before I find out the whole thing would be better off being replaced with a new one. I'll try to upload some pictures I have of it later today.
How nice of you to provide a relaxing spa for the frogs!![]()