If there are no fish in the pond, do you need the hydrated lime or can you just apply the Alum and wait for the PH to come back up and stabilize before stocking? Another question, if you have extremely high alkalinity already, is that enough to buffer the Alum without much PH change?
If there are no fish, Hydrated lime is less expensive, adds calcium, and will sterilize and turn the pond gin clear. It will make the pH go sky high at first, but it returns to safe levels, or normal in a couple weeks.
