Pressure regulators begin reducing the PSI once the minimum flow requirement has been met, so there needs to be enough flow running through the system for the regulator to work correctly. If you install a hose after the pressure regulator, and then test the pressure at the end of the hose, you will begin to see the pressure reduction. Regulators such as our Lawn and Garden pressure regulator (Item PRSG) needs a minimum of 0.5 GPM (30 GPH) running through the system in order for it to begin reducing the pressure to the chosen amount (either 10, 20, 30, or 40 PSI).