I came up with 125 m^3 here:

http://www.airproducts.com/Products/Gases/gas-facts/conversi...

But if you're going to criticize their math, you might want to double check your own math.

90 m^3 = 2m (height) x 6.7 m^2

(ok, 2m is a little low, 2.5m would be more comfortable.)