How long does an alum treatment last?
I've asked that many times. It's not cheap to get this done, and I obviously didn't want to waste money. The last rain we had I checked water coming in, and it was clear. Most of the water comes in through a alfalfa field. It was planted in August, but it's pretty well established. The wheat/ fescue I planted around the pond has come up nicely, so I am hoping for very long term clarity, at least in regards to the suspended clay.
My jar test indicated that the clay was going to stay suspended indefinitely.