Gary, I hear you on the air compressor. This is our second one in 13 years. The first ones diaphragm failed. I took the newer one apart and cleaned it eight months ago, replaced the seal and air intake pad etc. we used it even VERY recently as a point of air injection prior to the duke and did get up to 50 psi so I know it is in good working order. To boost the duke in particular, we had to re wire it to the solenoid valve vs the pressure tank so it would inject air at the appropriate time, but it only went up to 15-20psi. Our duke guy said we were limited by our pump size and needed to lower our gpm. Our pump is 7.6 gpm and the nozzles are rated for 4.5gpm. He told me to plug two, shoot for 35-40 psi then cap another if we did not reach that. He absolutely nailed that one. I think there are 6 nozzles. It does take a longer to fill but certainly smells noticeably better. I think the remainder is surely a post filtration issue.
What got me to call them was you suggesting the duke was not aerating all the gases. I didn't think so but I mulled it over for a week or so and did recall the lower psi. Thanks for putting the possibilities out there. Terri