Pump Noise After Filter Change

[HeyEng]

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 suspected, the old filters were nasty and absolutely covered in debris. The filter pressure before was 25 PSI and after is now 15 PSI. All good, right? Well...

Now the pump is making one helluva a noise. I would almost think that it's the sound of a bearing failing (similar to a gravel crunching sound). Also, the return flow to the pool...well, it's pretty crazy...almost like a spa. I think I am getting a full turnover in about 30 minutes (not really, but the flow is noticibly increased). I am not able to put the motor into low speed (that's another thread) so I am unable to tell if this sound would continue.

I am confused as to why a very quiet pump (under restricted flow) is now so freaking noisy. Any ideas?

 

[JamesW]

It sounds like it’s probably cavitation, which is excessive suction causing the water to convert into gas right in front of the impeller and then collapse back into water right after the impeller.

The sound is often compared to gravel being pumped or crushed.

The dirty filter helps prevent cavitation by reducing the flow rate.

The pump might be oversized for the plumbing or the plumbing might be clogged.

Make sure that the suction and baskets are all clean.

 

[HeyEng]

It sounds like it’s probably cavitation, which is excessive suction causing the water to convert into gas right in front of the impeller and then collapse back into water right after the impeller.

The sound is often compared to gravel being pumped or crushed.

The dirty filter helps prevent cavitation by reducing the flow rate.

The pump might be oversized for the plumbing or the plumbing might be clogged.

Make sure that the suction and baskets are all clean.

I thought that it might be cavitation but the pressure flow seems awfully high for that? Also, all baskets are clean. I have thought that the pump might be oversized for the pool and that's one of the reasons I would really like to get my low speed working, but as I mentioned...that's a whole other issue.

The sight glass in the pump basket is running clear...no bubbles at all, so I *guess* that would be a good indication of no leaking in the plumbing?

 

[JamesW]

Maybe get a 1/4" npt vacuum gauge to check the vacuum pressure to see if you're getting excessive vacuum, which might indicate a clog.

Note that the vacuum gauges might not be in psi. Inches of mercury are common units. So, be careful about the readings and the units of measure.