We don’t recommend fermenting under pressure with the Spike Unitanks or Flex fermenters.
The gas manifold is designed for sealing the vessel after fermentation so it can be pressurized for cold crashing, carbonating, and pressure transfers. We don’t recommend swapping your blow off tube for the gas manifold until early, vigorous fermentation has slowed down after a few days.
If it is attached during early fermentation, there is a risk that krausen will rise into the manifold and clog it. This could result in a failure of the pressure relief valve. If the valve does not work properly then too much pressure can build up and cause the lid to explode off the body and potentially cause serious harm.