40 amps should be PLENTY.
I run my 1/4 hp rotary vane pump (Gast 0523) on a 15 (or 20) amp breaker along with my dusk to dawn light with no issues whatsoever. I have actually amp tested the pump to near deadhead and it was pulling 10 amps, but it typically pulls under 5 amps. The inrush current is 23 amps, but only for a very short moment until the pump reaches full speed. I am pushing the envelope, but 40 amps of service would allow for a bigger pump, and some lights, and a radio, and maybe a fountain.
