I can't tell you where to get that amont of Alum but its apparently used alot in industrial applications so may wanna call some local chemical supply companies. As for application, I have read that people spread it behind trolling motor or small outboard allowing prop wash to mix it. Thats still alot of work if 1600 lbs is the needed amount. Iam in the same boat with my new 1/3 acre pond. Based on my research and past experience with a smaller pond I am going to focus on stabilizing the drainage basin and give it a few months to clear on its own. In my area, I will get lots of runoff the next 3 months.....just need to make sure the the water going in is clear.

-Jason