air/bubbles in hydraulic oil

[Hotrod1830]

I ran my 1830 for a few hours today to see if the fliud foamed up. It did not foam, but I saw what I thought was metal in the oil. I pulled it into the shop and pulled a sample from the tank while running. After some inspecting, it is air bubbles. Fluid settles out clean after sitting(clear container). My question, is the hydraulic fluid supposed to be 100% free of bubbles? I have looked for air leaks till im blue in the face. getting ready to pull the hydro pump and give it a look if its spposed to be free of bubbles. My charge pump is fed by the hydraulic return line after the filter, so any air in the system means my hydrostats could suffer. ( reason for noise?)

 

[earmuffs]

some models require a anti-foaming additive, make a call to a dealer and ask