i do not have a lot of out flow and the pond is all the way full.
That's a good thing. Too much outflow only wastes your chemicals.
In a pond that size with plenty of gypsum already applied, you can use 500# of alum with no worries. Just saying, beause it may not take that much. Try not to apply alum in areas where there are a lot of fish. It probably wouldn't kill them, but I guess it's not fun to get a snoot full of something as acid as lemonade.
