Janice from Manteca writes
Each BTI Mosquito Dunk covers up to 100 square feet of water. So if the water you are treating is a 20 foot diameter container, then you woud have 314 sq ft and would need 4 dunks. Keep in mind that BTI Dunks should be used only in containerized water, and they should not be used in water used for swimming.
Answer last updated on: 04/20/2018