Hmm... Not sure about your math. Did you mean this?

8.5 acres * 44100 ft^2/acre = 374850 ft^2

374850 ft^2 * avg depth 3 ft = 1124550 ft^3 (cubic ft)
1124550 ft^3 * 7.48 gal/ft^3 = 8411634 gal

So roughly 8.4 million gallons.

Our old pond project (updated 4/11/17)
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