First question I always ask, what is the customers goals, both short and long term?
Next I ask myself, are these realistic, can they be done, can I do it?
Do they conflict?
As for this pond, sounds like he just wants it back from invading plants. There will be many jobs like this. But no two are the same. Does this pond have a fish population?
This is not the ideal time for that treatment. In fact, it's close to the worst. Many of the plants are going to be dying back and going dormant anyway. It might make you look good, but it won't be from Fluridone. Is that the lowest cost solution?
Bear in mind that is a slow acting solution. Sometimes a 45-90 period. Where will that pond be in 90 days? Under ice? Will those plants be a problem then?
There are so many questions it is hard to give the right advice. But if it were me, and I still have a question about fish, I would use another fast acting kill it all product. Then inform him you will need to retreat with a slow acting long term treatment next Spring.
Others concerns and questions are, why? Why is the pond so full of weeds, is there some kind of nutrient loading problem? What if, you kill all the weeds and cause some nasty even worse algae bloom or blue green nightmare?
Short answer: No way I'd treat a pond like that with Fluridone this late in the growing season.
