Jebao SLW20 sometimes makes noise as if something got stuck in the fan?

[Subnautica]

I just purchased 2 of SLW20 model. I set them both running W1 (wave mode). But every 5 minutes they both make weird sound as if the fan changes rotation or something got stuck in it. Every time they do so, I can see a wave of water bubbles released from the powerhead. Both are doing it from time to time. Is it normal?

 

[tuco2018]

Is it pressed against the side of your tank?
My slw10 made slight noise when I first put it in,
It’s quiet now,
Noisiest thing is the im spin stream , can’t even hear my power head ,

 

[Johniejumbo]

How close to the top are they? Any chance they are pulling air from the surface?

 

[tuco2018]

Mine is about 4 inches from the top,
I take them apart every water change for a nice cleaning in ro water too

 

[Subnautica]

They are 3 inch under the water and no part exposed to the air. they are running very quiet, but occasionally make noise and release some bubbles out. Very weird

 

[Subnautica]

@tuco2018 @Johniejumbo

 

[tuco2018]

How strong are you running it,

move never ran mine passed half power on the knob,

 

[Subnautica]

How strong are you running it,

move never ran mine passed half power on the knob,

I have it at 6 out of 8 dots. dang that might be the reason :O

 

[pdxmonkeyboy]

Its pulling in air from the surface. But i think everyone saw that in the video. Lower it, problem solved.

 

[Subnautica]

Its pulling in air from the surface. But i think everyone saw that in the video. Lower it, problem solved.

Yeah I didn't see the whirl pulled from the surface. Feel so stupid now. My previous powerheads were always at this level (even higher up) and never had this issue

 

[pdxmonkeyboy]

Well, at least you know now

The only thing that can cause bubbles is sucking in air or a REALLY powerful pump that has such a negative pressure it will cause the air in the water to ...ummmm... i forget the word. It causes cavitation. This happens on some big return pumps like hammerheads.

Fill a syringe halfway with water, now put your finger over the end and pull the plunger up. See all the bubbles...negative pressure. Your essentially boiling the water.

Anywho...