Water meal covering one acre will be a difficult project. Firstly your water meal will be hard to eliminate with just one application of Clipper. IMO you will need several applications as the watermeal reappears due to resprouting of accumulations of the old seeds in all the bottom areas. Plus you will not kill all of it in the first few applications. With just one 2 gallon hand sprayer you will have a very hard time reaching all areas of the watermeal infestation. For good kill of these plants you want good even coverage of all the infested surface layer. Don't plan on the Clipper to disperse and spread to kill adjacent areas because Clipper degrades very quickly in hard (alkalinity) water common to Ohio. Plus when the surface accumulation has layering of the meal it is hard for the spray to reach the bottom layer.
Depending on the area of meal coverage, use 6oz to 12 oz per surface acre. In your 2 gallon sprayer I would mix about 1oz of clipper for each tank full. Then adjust the amount based on your results. You might want to invest in a tank power sprayer because you will need numerous future applications of Clipper to control water meal. Even this sprayer is too small for treating a one acre pond.
https://www.ruralking.com/country-way-economy-atv-sprayer-16-boomless-sao-h3-015b-rkSpray prep. 1. be sure your spray water is pH 7 or lower as Clipper degrades very quickly above pH7. I would use rain water or water diluted with distilled water in the sprayer to get the pH lowered. It is best if your pond water is not over pH 7.5 for best results. pH near 8 reduces the effectiveness of the Clipper. If it were me I would wait until the meal is wind driven toward one end and then spray it since you don't have a power sprayer to reach far out into the pond. Wind accumulated layers of meal will require multiple treatments each around 7-10 days apart.
Commentary. Water meal is a sign or environmental indicator of over or very high nutrient enrichment - hyper-eutrophy. Generally water meal and duckweed only appear in old or aging highly eutrophic enriched ponds. Both are common locally for me in drainage ditches that receive septic tank effluent. These ponds are due for rebuilding because the years of accumulation of organics and nutrients (high or large nutrient sink). The plant problems will increase and become greater causing more weed and water quality problems due to all the years of accumulated nutrients. These ponds are aged and progressing toward swamp-like conditions. The short term or long term plan should be to drain, rebuild and deepen the pond to return it to new young characteristics of good water quality with minimal weed problems. Dealing with this type of pond will be costly and it will drain your wallet for constantly buying herbicides plus they cause high accumulations of chemical substances in the pond. Some call it contamination.