Chris, I have far less exposed are than you and after one medium rain, all the money spent on alum was wasted. The Alum does not stay in the water column. As the negatively charged particle attach to the positively charged aluminum, the Floc falls to the bottom and only helps to settle back out what is disturbed, ie like when you walk in it after clearing.
Been there done that! Wait till you get vegitation to control the erosion and run-off. Try about 15 ton of ag lime thrown into the pond and around the edges---it can only help.
