I am new to SPAs and this is a SPA that came with the house I bought. It's a very old K2 HydroSpa. One of the jets was flowing water but not aerating so I was opening and closing the two nozzles on that "leg" to see what was up. When I turned the pump back on, water was now coming out the air vent control and neither nozzle is aerating.
I took a shopvac and blew air into the vent thinking I had "flooded it. It clearly bubbled out both nozzles. But when I started the pump back up, it continued to flow out the vent as well as the nozzles.