This seems to be a pretty hot topic, and a very good read. I must ask though, as I research Alum for pond use, most of what I find is mixed with a buffering agent, in most cases this appears to be sodium carbonate (soda ash) at around 20% of the total volume. I happen to have about 400lbs of sodium carbonate left (that I sealed my pond with) so I'm wondering about obtaining the alum and mix myself. Lime has always been a no-no in my location due to our soil make up so I'm guessing I'd be better off using the soda ash..?? I have been asking around about Alum and I haven't found a source anywhere close. I assumed being in the middle of mainly Ag country I'd be able to obtain enough to do my 2.5 ac ft pond. Going to need to find a source of Alum first I guess. Any thoughts on the sodium carbonate?? I didn't see that mentioned by anyone as a buffer for Ph control..
