Recommended pressure for pool circulation?

[mas985]

One other thing to note is that the filter's pressure gauge reading is dependent on the elevation of the gauge with respect to the pool's water level. So if it is in the basement with the pump, it will read about 4 PSI higher (9 ft down) than at ground level.

Also, a pump & motor combo is designed for best efficiency when operating in the middle of the head curve. This is somewhat counterintuitive but a motor's load actually goes up with lower pressure and higher flow rates (right side of head curve). A pump will draw the minimum amount of current when it is dead headed at zero flow. It will draw the maximum amount of current at the other end of the head curve near the maximum flow rate. So as long as your operating point is somewhere around the middle of the head curve, you are not overdriving the pump.

By changing the clearance in the impeller, you are changing the dynamics of the pump/motor interaction which will also change the load on the motor. It is probably like stepping down the impeller size on an existing motor. Pressure and flow rates both will drop (i.e. the whole head curve changes) and the load in the motor will drop but this also reduces the efficiency of the pump. I don't think it would damage anything but it really isn't necessary.

[GWNorth]

I would never have thought about higher pressure reading with guage below water level. Great information to know now.

I see what you about setting the impeller clearance larger. I like to avoid future problems whenever I can but sometimes go too far the other way and end up causing other problems. I will probably set the impeller back to how I had it which was closer to instructions on how to set it.

Now that I know that 20 psi isn't out of a normal range, I can be more corfortable with the higher pressure.

Thanks for all the info.