Yes at 30/50 that tank should hold about 3 gallons of water. But if you set the CSV1A at 45 while running 3 GPM, it won't close down to 1 GPM until about 47-48 PSI, so 30 seconds sounds about right. Set the CSV to 38 PSI while using 3 GPM, then it will close down to 1 GPM at about 40 PSI. Then you would get about 90 seconds of run time. Usually we just set the CSV in the middle at 40 with a 30/50 switch, and you get 60+ seconds of run time. But with a CSV the amps drop when the flow is restricted, so you don't need a full minute of run time for motor cooling. It is nice to have 60 seconds when you can, but 20-30 seconds is not going to hurt a thing.