Well, according to my maths my pool is closer to 26k gl (where they got 40k is beyond me lol)
Shallow- 18' x 26' x 3' = 1,404 cu ft x 7.48 = 10,500 gl
Deep- 16' x 24' x 5.5' (avg) = 2,112 cu ft x 7.48 = 15,800 gl
10,500 + 15,800 = 26,300 gl + couple hundred for steps would put that around...