In the pool. I dropped it while installing a Hayward through the wall skimmer. My pool is a lovely shade of green, and I can't see it. Blindly scooping with the net has hit the screw, but wasn't able to pick it up. I tested the remaining screws, and the are not magnetic (was going to try a magnet on a string).
Can the screw be safely vacuumed, or is it time for a swim in the swamp?