I also want to keep them off of the patio. I know, they can fly, but I need a deterrent.
I (yes me alone, The Engineer is out of the country) took the pool fencing and blocked off the side yard. Then I filled in the dirt with ten bags of top soil. I put a short green fence around the entire pool. The ducks have to have water to drink 24/7 so they will now be forced to go to the canal.
Yes, they do fly over it, but for the most part, they are obeying the new world order.
Go Be Ducks! :)