I have a Polaris 9300 robot that is in the shop. (FYI: apparently, you are not supposed to use the robot to get the fine particles off the bottom - it is for maintaining your pool only. Seems ridiculous to me to spend all that money...)
As a backup I may purchase a manual vacuum that goes through my filter pump. I have a 21000 gal gunite pool with Hayward cartridge filter. I have no idea how to isolate one of our 2 filter baskets but I can ask that later if I get a manual vac.