Based on the Flow Rate of the Filter your builder is right.
However, for a pool your size I would have recommended a Cartridge filter w/ at least another 2.5 to 3x more sq. footage. The reason why is that even though the flow rate is sized properly for the pump the larger sq. footage filter will allow for longer filter cycle times in between cleanings.
Because it will get dirtier faster you will have to keep the filter element cleaned regularly or the system won't work properly. No filtration, no flow, no vanishing edge.
Disadvantage of the larger filter is the cost of the elements when you have to replace them. Then the smaller one can look a bit better.
Either way I would suggest having a second element so you can sitch it out when you have to clean the dirty one.
Thanks
God Bless
Scott T. Roodbergen
Regional Sales Mgr.
Waterway Pool Products