Using a sprayer is the most effective and recommended method to apply Weed Plex Pro, when treating for submerged and floating weeds in your pond or lake. Please note, this is a non-selctive herbicide and can burn or kill plants it comes into contact with. See labeled instructions for amount of diquat needed. Application rates will vary based on overall size and depth of the pond; in addition, identifying what type of weed your are trying to treat. It is necessary to wear protective clothing and eyewear when applying and avoid comming into contact with mist.