I doubt 100 pounds will give you the results you like, or hope for. When applying Alum/hydrated lime, you need to remove ALL the suspended clay. A partial clearing is indeed temporary. I use an average of 200 pounds Alum and 100 pounds Hydrated lime per acre foot of water...some ponds have needed 4 times that amount, yet only one pond has needed retreating afterward. That one pond had a neighbor spread bare clay on 2 acres of watershed. That client's solution was to buy the property...lol