I used some of it, to remove the excess winter leaves and debris, did not feel like netting the bottom and sorting out the snails tads bugs. It worked great, I did a test, put a little amount on a few of the thousands of tads I have, they did not even notice it, no snails died the fish did well.
You need to keep air going or water flowing, and not dump tons in at once. I did an area at a time of the bottom, like 1/4 of the big pond bottom at a time. The 1000 gallon stock tank I did the whole tank, used around 1/2 lb for that tank.
The stuff just floats, up use a fine weave net, I used my swimming pool leaf net. Have a place to dump it, it floats up within seconds and keeps coming.