1.5 GPM, 3.0GPM, 6.0 GPM
The formula to use is:
Example for 4 each 1.3 GPM heads and 2 each 2.6-GPM heads,
area dimensions 37′ x 74′:
How long will it take to apply a certain amount of water?
divide how much you want to apply (no more than .75 inches) by the above answer (inches per minute)