8249 US gallons, approx.
About 17,950 gallons.
280.298 Imperial gallons
250 ft3 = 1870.13 US gallons
To fill this pool to a depth of four feet you will need about 7,646 gallons of water. If you decide to fill it to three feet deep, the gallons decreases to around 5,735.
If the pool is a constant 9 feet deep the total volume would be 48,600 gallons. However, if 9 feet is only the deep end and the shallow end is 3 feet deep, the gallons changes to 32,400 gallons.
A maximum of 1,196.88 gallons of water.
1869 Imperial gallons, approx.