If there is a bar-wide outage of CO2 and you suspect that the big tank might be low, you can confirm on the big tank by examining the “bubble gauge” on top of the tank itself. The yellow indicator line in the bubble gauge should be between the green light at the top and the red line at the bottom. If the bubble is at or below the red line, then you will need to switch the bar’s CO2 to the small tanks.
If the yellow indicator float is hovering towards the bottom of the tube (near the RED line), then the tank is at or near empty:
Whereas if the yellow indicator float is hovering towards the top of the tube (near the GREEN line), then the tank is at or near full:
Our big CO2 tank is auto-filled by our vendor on a regular basis, so the tank running low is unlikely.