I spray at 30 psi. The pressure gauge should allow extra liquids to go back into the tank. On mine, you can set it for desired pressure. The amount of pressure needed will depend upon hose thickness, # of nozzles and their pattern (I use flood nozzles). With 6 nozzles, 30 psi is all the 2 gallons pump wants at 5 MPH. I spray my yard, church yard, test strips in fields or use wand to direct spray weed killer on poison ivy. Key is to always clean/rinse after use or chemicals will dry in places you can’t clean.