Calcium Hydroxide is fast acting. It's also called "hydrated lime". it's about 6 or 8 bucks at a feed store. if you have a small plot and need something to work instantly, try a bag or two of this. i know that i mixed some up in a 15 gallon tank and sprayed it on my lawn. the wand for my sprayer leaked. the next morning most of the skin was eaten off my hands.