I’m wondering if anyone has run into the following issue, any advice is appreciated.

When priming the pump with a high flow, a very loud and rhythmic knocking noise takes place. I lowered my priming flow rate to 5ml/min from 10ml/min and I could still hear the knocking.

I’ve applied a pump rebuild kit.
While disassembled, cleaned all areas of the pump.
This only temporarily solves the problem, after running the pump the noise will come back on its own.

The solution I’m running through this pump is mildly alkaline if at all. Nothing looks corroded when I disassembled the pump.

This issue might be causing some noise on my baseline but nothing too dramatic. Although I’m worried this will becoming a bigger problem.
I’m curious if anyone has run into this issue.

Thanks in advance!