I’m about to start my first autopot grow in a few weeks, and I’ve stumbled across and run searches on this topic a few times over the past year and I’ve never really seen a definitive answer... I recall reading that a max size would be 3x3 for a single aqua valve. I’m thinking of finding 2x2 or slightly smaller trays to put 2 in a 2x4 and run 1 gal airpots in the trays using one aqua valve per tray.