I pressure ferment all my lagers. I set the spunding valve to 7 PSI and vent the co2 through a beer bottle with water in it ( I vent through a bottle mostly to monitor fermentation). After 7 days or so at 45-48F/ 7 PSI the air lock activity slows, I raise the temp to 55F and the pressure to about 25 PSI and let it buck. If you raise it to 62-68, then raise the pressure to 28-30 PSI. The beer will finish in about 2 days, but the air lock activity continues for longer since the beer is still de-gassing. After about a week of 25 PSI (14 days total), I crash the beer to 32F and 24 hours later I taste and check the carbonation level and adjust if need be.The beer will continue to de-gas for longer than 14 days and it looks like it's still fermenting, you can check you gravity at that point, but I've done it so many times I don't bother.
It's not very scientific, but the spunding valve acts as gas regulator. You don't need to be too worried about it, it can be adjusted after crashing. I let the beer lager in the uni-tank and taste it as it ages. After a while, I transfer it to a keg. I could just as well bottle it from the uni-tank, but I prefer the beer to be in a keg.