hd82, the alum actually lowers the ph, making the pond more acid. Since it is already pretty acid, just put the quicklime in 1st, then the alum. Use a little more than 1/2 lime per unit of alum and the pond will get to more neutral for a while. Long term, this fall add 2 or more tons of ag lime in and around the pond. Next spring, the ph and hardness will be better. Depending on the average depth and your depth of visibility, probably about #50 alum and #30 hydrated lime should do the trick. It is sort of like all or nothing with alum. If the 1st try doesnt do the trick, a little more may. Once the electrical charge is great enough that the particles stick together enough that they sink, then the pond will clear in a couple of days.
Dont be afraid of the alum, just always neutralize it with quicklime.
Good luck.
