Air in Pump Basket

[king908]

Have a Pentair Variable Speed Pump. At High Speeds I do not see any air in the basket.
If I run at 1100-1500 RPM, I do see that there is Air in the Basket?
Is this normal at lower speeds?

 

[Richard320]

Seems like it. poll-for-users-of-variable-speed-pumps-please-read-t30272.html

I used the search box using variable bubbles strainer and found several more.