If you aren't careful, your conical could suffer from the dreaded "suck back" of Star San if you cold crash with a blow off tube attached.  This is due to a vacuum effect that is created when the temperature of the beer is lowered and pressure drops inside the fermenter. Star San in finished beer is no good!

Simply remedy this issue by removing the blow off tube and capping that port on your conical lid.  Be sure to attach your All-In-One PRV or gas manifold, if not already attached, to your PRV port before you cold crash! Apply a small pressure (~5psi) and then cold crash your beer. The applied pressure will prevent a negative pressure from occurring in the tank due to the temperature drop.