I have no idea where I came up with 244. That's what happens when you do this stuff at work and pay only half attention. [:-]
I thought I might be wrong which is why I asked.
Recalculating with 144 instead of 244 results in 29.22 oz/sq ft
That's bloody close enough to 30.
All of this is estimates until I get the thing weighed.
Thanks person with the long name!
G

PS: I always balance with the tank empty.