Hi Cash,
Could we have an update? Did the system keep working for you? What were it's pros and cons?
I could see using the concept with a "flood and drain" quackerponics system by using storage tanks with float valves to keep the pond at more or less the same level, while holding, then flooding grow beds. I suspect that just like with fish, you'd need an awful lot of growing surface and plants to keep up with messy ducks. Looking at my ducks, there will be much more solid waste - dirt, sand, bits of grass - in duck water than fish water. That's where Cash's simple system that grows biomass which can at least be useful as
mulch seems to make sense as a "living filter" which could be used at the start of the cycle with the pre-cleaned water then going through the food beds. I suspect there would still be dissolved nutrients for a useful number of edible plants.