The water is just the carrier. Ignore the water for just a moment.
Your yard is 10k (based on your profile). If the dosage you're going for is 0.5oz of prodiamine per 1k of lawn, then you would be applying 5oz of prodiamine, spread evenly as possible across the whole area.
Back to the water, there is usually a minimum amount. In this case, you could use ten gallons or a 100 gallons, the goal is even application of the chemical.
Your yard is 10k (based on your profile). If the dosage you're going for is 0.5oz of prodiamine per 1k of lawn, then you would be applying 5oz of prodiamine, spread evenly as possible across the whole area.
Back to the water, there is usually a minimum amount. In this case, you could use ten gallons or a 100 gallons, the goal is even application of the chemical.