I may know of some who use Karmex(diuron)in their ponds resulting in crystal clear water and no weeds, and no algae. It is cheap but the negative effect on the pond ecosystem, required permit, and 10 day application process didn't seem worth it. I think the guys I may know just mix it up in a bucket and dump it in. Pretty scary and I'm sure EPA penalties would be steep if they were caught. I have read of Southern catfish farms using it to control blue-green algae but they did so under a special temporary permit. I asked the local fish farm about Karmex and the guy became pretty irritated saying "YOU WANT FROGS WITH FOUR LEGS!?!" ...well...yes... I didn't really answer him but I think he meant more than four legs or four eyes or something.
"The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge." Stephen W. Hawking