Back pressure causing cavitation?

[tsav]

So it's nearly midnight now and my sump return pump on my nano tank is vibrating form the inside, loud enough to wake the wife and I.

It's a Mag 3 pump and I'm using a gate valve to dial it back quite a bit. I'd say it's about half way open. Then it has to travel 3' up to the tank.

It was running smooth for a few weeks now. This is a recently setup system. I had a Mag 5 pump there and it started vibrating from the inside only after a few days before replacing it with the Mag 3.

I'm assuming its cavitation caused by too much back pressure. What do you all think?

If it is, I'll have to order a lower gph pump.

[tsav]

Bump

[das75]

always read no concerns restricting flow with a valve on output, would assume if caused problems would have been flagged by now.

Good inlet path, no elbows just before pump, pipe isn't reduced or plugged?

[mcgyvr]

I think you should fix the reason you have to dial back a pump..
And while you are doing that check to see if you cracked the impeller/magnet.

dial back a pump = you messed up already.

[tsav]

I think you should fix the reason you have to dial back a pump..
And while you are doing that check to see if you cracked the impeller/magnet.

dial back a pump = you messed up already.

We'll I could see how you could make that assumption but the reason I'm dialing it back is because the mag 3 is a it too powerful for a 7.5g display lol. Blows the sand everywhere if I don't throttle it back.

Both pumps are about 9 years old. Maybe they've just reached the end of their life.