I stocked my 3-acre pond last fall with 40 White Amur - which were maybe 12" in length. We had a fairly cold winter with thick ice frozen over the entire pond for probably a month here in Indiana. My pond has a deep spot around 18'. This past spring in late May I added some Aquathol (1 gallon) on only half of the lake's perimeter thinking the other half could have the weeds. I noticed that it seemed to knock out most all of the fresh green that was starting to grow on the bottom - even on the other side that I didn't treat. I treat the entire lake perimeter with Cutrine Plus once a month during the algae growing season and avoid any copper sulfate. I see tons of spawned fathead minnos that I added in the spring, but I have yet to see a single grass carp feeding anywhere. Is it possible they are all dead??