According to the manufacturer, 1 x 5 oz pack of the Prime Source Aqua Blue WSB Colorant will treat 1 surface acre up to 1ft in depth. When treating a body of water that has a wide range in depth, it is recommended to take the average depth when calculating how much to use. To treat a 10 acre lake that ranges from 3ft to 10ft in depth, you would need 60 packets of Prime Source Aqua Blue WSB Colorant.  10 acres x 6ft avg depth = 60 packets.