We use a 3/8” Goodyear Neptune hose. We use a Fluid systems Ball bearing swivel KR #SW0260 with 3/8” coupler on the downstream side of the swivel in the middle of the hose, we use the same swivel on the gun. With the swivel on both ends of the hose it helps the hose turn for the customer and keeps it from getting twisted. We do the same on the Foam brush hose.
Paul I’ve had the same problem over the years. I use the Zierden 204 boom with the heavy spring on the end of the of the boom. When I install a new boom pipe, all it is is 1” electrical conduit, I bent the end of the boom down at the end to about a 22 deg. angle, I also slip a piece of electrical shrink tubing over the hose where it comes out of the boom.