Thank you very much for the information!
As for the size of the motor, I got 0.5HP from the information on the fly spray system retailer web site. The 0.5HP was for the large system, which may have, say 50+ nozzels runnning, and maybe 150ft or more of line, so 30 gal/min seems reasonable...
I'm sure asking this question here is a bit of overkill, but I hope someone will point me in the right direction.
I hope to use an automatic fly spray system with either a 0.33 or 0.5 HP moter to control mosquitoes in a small three sided shed for horses. The shed is farther from the main barn...