I ferment under 10psi in my Spike CF-5 using the Blichmann Spunding Valve. Once FG is reached, my blow-off tube starts to suck the Starsan slowly up the tubing toward the pressure gauge. I have my co2 tank connected at 10psi and I can confirm positive pressure by loosening the pressure adjustment knob at the spunding valve, sending the Starsan back down the tubing. The environment in my brew room maintains a constant temperature so I can't blame it on that. Does anyone know what might be causing this vacuum where there should be none? Thanks.




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