The hydrated lime will kill the fish much better than alum , will offset the condition of the water once the alum is added and will leave the water in a condition that you can stock into. The ag lime will add buffering (alkalinity) which you most likely need given your location. All 3 together will help clear the water.

I know (they are friends) the guys who wrote the MS manual and who updated it. I have great respect for them as they are great FS and people. They are doing their job well. The material by definition is basic as it must cover without substantial risk of error the vast majority of ponds in MS . USDA and Co-Op Ext. are farm agencies and write/publish for ag/aquaculture purposes as they are charged to do. Depending on the goals and the situation the advice is to general. Even in its updated condition it is behind the cutting edge in pond mgt. For example I use it for general info but not for stocking guidelines for my pond to my goals and conditions. Also know that the basic info upon which it is based is from ponds used for food production (1930-60) as that was the charge (instructions) to the writers. It has been updated for recreation but has the same baseline. None of the private FS that I know use those guidelines as gospel. Instead they look to the pond in question and the owners goals and customize a plan to fit the circumstance. See Greg�s comments for an example.