Mark,
first off make sure you are dealing with coontail. you may have another weed that is cheaper to treat. lots of good weed ID stuff online
make it easy on yourself. look at the area of weed infestation. You have a 1.67 acre pond, lets say you have 1 acre of weed coverage. Read the label on the Reward to determine rate for the weed you are trying to kill, usually its about one gallon per acre. or one quart per 1/4 acre
therefore
2 quarts per 1/4 acre = 2 gallons per acre. if you are not killing weeds with this rate of Reward you probably are not going to kill them with Reward.
measure off 1/4 of an acre, one easy way to remember your corners is to use those floating fishing markers or duck decoys. once you have a good idea of where exactly 1/4 of an acre is then spray 1-2 quarts (depending on the recommended rate) over the entire area. it does not matter how long you spend just as long as the 1-2 quarts is evenly applied over the area. you can mix reward with just about any amount of water to help you apply it evenly, 2-4 gallons per quart should be plenty. make sure to use clean water in your spray tank, not pond water. also make sure the pond is not muddy from rain, wait for it to clear before applying reward. wear gloves, goggles and all other saftey equip. wait 2 weeks, Reward works pretty fast. My books say Reward is excellent for coontail, I have treated it a few times and got good results.
