Pump Noise After Filter Change
This morning, I installed new cartridges into the filter. I debated cleaning the existing ones, but knowing how the previous owner had blown off all preventive maintenance around the rest of the house, I had an idea that all-new filters would be a prudent move. Replacement was no issue..and as I...

I found this old thread, and hope someone can help me better understand. I am having this problem. On Saturday my pressure was at 12, which was close to 10
psi over startup in my two year old pool. I pulled the cartridges, hosed them down, and let them soak for a couple of hours in dish soap as described on TFP before giving them another good rinse and reinstalling them.
At first it was great. The psi was at 4. Awesome! Then I noticed lots of little bubbles from one of the returns. I did research here and figured I had a suction side leak. Sure enough, the o-ring on the pump pot had some small debris on it. Cleaned that off and put the lid back on. Bubbles gone. All returns feeling and looking normal.
This morning psi is at 6. Returns look and feel great. But the pump is vibrating/rattling/knocking. I don’t know how to explain the noise. Also the water rushing under the glass of the pump pot lid is perfectly smooth; it’s hard to even tell there is water there. I had to turn off the pump to see that it IS full of water. This is odd because the pool is two years old and water has ALWAYS kind of thrashed and churned around under that glass, not in a vortex - just lots of water churning.
So what’s normal? The water churning under that glass lid? Or perfectly smooth? What caused the change?
If the newly cleaned filters caused cavitation, why didn’t the clean filters last season (when they were brand new in their very first season) cause cavitation? Doesn’t that indicate that the pump is NOT oversized? Does that mean I have a clog somewhere?
I can’t figure out how to post videos here, but I have video of the noise my pump is making now. I’m scared of letting it continue to run in case it destroys my impeller. I also have video of the water churning under that glass lid last season. It’s always done that so that seems normal to me.
Thank you (AGAIN) for amazing advice here.