if your getting air bubbles with the air valve closed you probably have a leak in the air chamber or tubing fittings
is your water level (without air bubles) in the right range? about 1" into the first clear chamber above the gray box?
sounds like your getting enough water flow, so I doubt it's the pump, but that thing will suck in a ton of air and pull it in from anywhere it can. Again my guess is you need to check the fittings on htat air chamber both the tubing fittings and the union on the top.
is your water level (without air bubles) in the right range? about 1" into the first clear chamber above the gray box?
sounds like your getting enough water flow, so I doubt it's the pump, but that thing will suck in a ton of air and pull it in from anywhere it can. Again my guess is you need to check the fittings on htat air chamber both the tubing fittings and the union on the top.