anthropic - Reward is a contact herbicide. I prefer it over copper based products.

From Aqua Plant

Reward is a liquid diquat formulation that has been effective on pondweeds and is very effective if mixed with a copper compound. It is a contact herbicide. Contact herbicides act quickly and kill all plants cells that they contact.

Cutrine Plus, K-Tea, Captain, and Clearigate are all chelated or compound copper herbicides and can be used in a mixture with Reward or Aquathol K. Other chelated or compound copper formulations are available but are not linked to this web site.

Aquathol K, and Aquathol Super K are dipotassium salts of endothall and comes in both liquid and granular formulations. These endothall products have been effective on pondweeds and can be mixed with copper compounds for additional effectiveness. Contact herbicides act quickly and kill all plants cells that they contact.