I'm certain that my fiberglass pool is at minimum 15'8" X 34"...it is pretty much rectangular, has at least an 8ft. deep end and 3ft. shallow end. The sides are sloping in the deep end. When I do my calculations on the pool calculator...I keep backing into the calculation that I have approx. a 15,300 gallon pool. Is there anyway this is possible?? I was at 12 FC and was trying to get to 15 (based on the assumption of a 22,400 gallon pool). When I added 1 gallon and 1 cup as directed and waited for an hour, my new reading was 16.5-17.00. The only way to reconcile that increase using the same amount of chemical was to lower my gallons to 15,300. Something doesn't seem right?? Surely the pool is larger and closer to 20,000 based on the measurments?