I monitored my pH prior to adding the Alum and was pretty much consistent at 8.3. I added one Hydrated lime for every two sks of Alum and the pH dropped to a 7 during the alum additions and after the Alum additions. I would add lime when adding the Alum. Lime is cheap insurance. I can not make any recommendations but I can say this was my experience at my pond. Hope it helps.
