Internal pumps: is cavitation/creation of air bubbles normal (and good/bad?)

[erwin123]

I have an internal pump in my low-tech aquarium that constantly generates a stream air bubbles but is not noticeably noisy.

I wondered how a pump can generate air bubbles if it is fully submersed (where is the gas coming from?), so I checked the internet and it says this is pump cavitation caused by changes in pressure etc and is a considered a "problem"

From the perspective on aquariums, I'm also wondering if this is good or bad 🙂

 

[MichaelJ]

I have an internal pump in my low-tech aquarium that constantly generates a stream air bubbles but is not noticeably noisy.

I wondered how a pump can generate air bubbles if it is fully submersed (where is the gas coming from?), so I checked the internet and it says this is pump cavitation caused by changes in pressure etc and is a considered a "problem"

Hi Erwin, what "pump" (brand/model) is it? Is it like an internal filter, or just a circulation pump? There is a physical phenomenon called cavitation, but I doubt thats what we are dealing with here, but we never know… the Navier-Stokes equations covers a lot of strange fluid phenomena.

Cheers,
Michael

 

[erwin123]

Hi Erwin, what "pump" (brand/model) is it? Is it like an internal filter, or just a circulation pump? There is a physical phenomenon called cavitation, but I doubt thats what we are dealing with here, but we never know… the Navier-Stokes equations covers a lot of strange fluid phenomena.

Cheers,
Michael

Hi Michael, this is a video of the bubbles coming out of the pump. As the pump is fully submersed, it puzzles me where they come from, only thing on the internet I've found is a reference to 'cavitation'

 

[foxfish]

It just shows that there is lots of oxogen in your water, cavitation is common in many situation, it occurs when the propeller or impeller is spinning faster than the water can flow.
Very common on boats when the boat accelerates the prop will Initially spin up and make lots of bubbles….. a bit like wheel spin on a car.

 

[MichaelJ]

It just shows that there is lots of oxogen in your water, cavitation is common in many situation, it occurs when the propeller or impeller is spinning faster than the water can flow.
Very common on boats when the boat execrates the prop will Initially spin up and make lots of bubbles….. a bit like wheel spin on a car.

I’ll take that explanation to the bank!

Are you related to or studied under Sir George Stokes, 1st Baronet, or just pretending ?

Cheers,
Michael