I have or have access to 13 tanks they all have duck weed all 13 tanks hold birds and the birds I clean all have snails in the crawl
This. You don’t necessarily have to plant something that produces a seed head for ducks. A lot of underwater vegetation will indirectly provide a food source, such as snails. Granted, a shallow tank that you have water control of planted with millet, rice, BYG, etc. would be a better option for ducks. One of the tanks I hunt has hydrilla and the ducks were constantly foraging for snails. Widgeon, greys, mallards, etc. I think the only species I didn’t shoot off of that tank this year was a redhead (besides the odd balls).