I am in the process of replacing a rapid dayton vertical deep well jet pump. This pump currently works but is leaking around the impeller shaft coming off the motor. So I have decided to replace it along with the water tank. I purchased a 1/2hp goulds VJ05 pump to replace it. The rapid dayton is also a 1/2 hp pump so I thought that would be adequate. Well last night I replaced pump but the VJ05 would not pump up pressure past 40psi and then would not kick off. The rapid dayton looks like it might be a multi-stage pump where the VJ05 looks like it's a single-stage pump. My question is would a multi stage pump be what I need? Gould makes a SJ07 which is 3/4hp. Just want to make sure I am going in the right direction. I ended up putting the old pump back on last night and it had no problem pumping it back up to 50psi. Thanks for any info.