Is ~ 4 lbs propane enough

[cdunn1221]

I have about 4 lbs propane left in tank Is this enough for all grain BIAB on dark star burner?

Any help would be appreciated

 

[MaxStout]

Doing the math, there's about 21,600 BTU per pound of propane. Four pounds is 86,400 BTU. The Dark Star delivers 54,000 BTU, IIRC, so 86,400/54,000 = 1.6 hours full blast with your propane, more time if you don't run it wide open.