Bill - I'd really like to know WHO is promoting the use of Karmex for aquatic treatments!!! Besides misleading good folks like yourself, that person is also violating Federal law as well as providing another point of attack for the anti-pesticide factions (via product misuse). Take a guess at the biggest reason why Dursban is no longer available to the retail market....
Do yourself a big favor and direct your questions (and business) to a chemical dealer who isn't proposing that you use Karmex in your pond.
BTW: I sell Karmex (diuron), but will absolutely refuse to sell it to anyone who indicates that their intended use of the product is related to pond treatments.

Kelly Duffie
Cypress, TX