How do you know your pool pump is working properly?

It is a vacuum. It should be picking up fairly well. That is what is was made to do and be sold as. If it is not, then check your filter.

I have a DE filter. I backwashed it and put more material back in and then the vacuum is working much better and very obvious.

I also have found that the recirculate setting is much better for vacumming if you have a return line type of vacuum. The flow is much faster and therefore the suction much faster.