Blueline 70 loud and vibrates

[BUNKEY]

I purchased a new BL-70 about 5 years ago form my 150. I have about a 14' vertical climb for the 1" return. I had to throttle the pump back with a ball valve to about 60% to control flow. It was always loud when I did not throttle it back and would pulse every second or so like it was not balanced or something, if my valve was not set in a perfect place.

I upsized to a new 210 and put a different return system in. I can now handle much more flow, but can't open it up anymore because the noise and vibrations are terrible. I have taken it apart several times and everything looks fine, nothing to ever take out and no obvious damage to the propeller.

I also have a 90 degree return to my sump so I can recirc in the sump if I want to. This is simply an open PVC pipe connect to a ball valve with a 90 degree from the main vertical return. If I close the main tank return and open the recirc valve it does the same thing. If I do not throttle it back 50% it is unusable from noise and vibrations or pulsing.

In summary: Open valve 80-100%: vibrates very badly, open 50-80% pulses like "wu...wu...wu...wu" every second or 2, open <50% pretty smooth and quiet.

It seems like it should not do this. I have heard my local stores pumps and they don't sound like this. Should I replace the prop or buy a new pump? If so, another BL-70 or something else? Noise is not that critical as it is in my shop in the basement, but these vibrations travel all the way to the second story.

Thanks,

Jim