# Powerheads blowing bubbles



## cichlidpastor (Jun 20, 2009)

My powerheads have started blowing a lot of bubbles (the little small ones). Does anyone know what can be done to prevent this?


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## car0linab0y (Aug 10, 2009)

are the power heads near an air stone or HOB? there have to be bubbles going in to get bubbles coming out.


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## steelers fan (Jun 26, 2009)

also do these powerheads have a vent?

some have a vent you can attach a hose to and run the hose outside the tank to suck in air to create what some think is the cool bubble effect...if the water level gets a little low this vent can suck a little air and may be causing your situation.

pardon me if you already realize this


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## cichlidpastor (Jun 20, 2009)

steelers fan said:


> also do these powerheads have a vent?
> 
> some have a vent you can attach a hose to and run the hose outside the tank to suck in air to create what some think is the cool bubble effect...if the water level gets a little low this vent can suck a little air and may be causing your situation.
> 
> pardon me if you already realize this


Carolinaboy, no they aren't near an HOB

And yes they have hose vents, but they are well under the surface.

Just a little more info. I am using powerheads without prefilters of UGF just hanging them in the tank for flow. They are older marinelands. It's just odd that they just started doing it and both them at that.

Could it be due to salt in the water? I do use epsom salt.


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## cichlidpastor (Jun 20, 2009)

Here's something else. When I shut them off for a few seconds and turn them back on they run clear and clean for about 10 seconds and then they go back to blowing bubbles again. Weird


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## KaiserSousay (Nov 2, 2008)

IÃ¢â‚¬â„¢m wondering if you could have finally got enough gunk on the impeller vanes, or housing, to cause cavitation.


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## PfunMo (Jul 30, 2009)

I think I would go with John's thinking and try cleaning the impellers to see what that does. While it doesn't seem natural, one can get bubbles without getting air from the surface. The salt may be adding to it a bit. My brackish tank gets more foam on top from the same equipment as my fresh. Probably takes a real guru to explain how it can make bubbles without getting air from the surface, huh?


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## car0linab0y (Aug 10, 2009)

what kind of filtration/aeration are you using? looking at my 55 (it has a spray bar) it could be that micro bubbles are building up inside the power head and forming an air pocket.


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## KaiserSousay (Nov 2, 2008)

*While it doesn't seem natural, one can get bubbles without getting air from the surface*

Think of a boat prop spinning up..lots of bubbles develop, even on a sub, 300ft. down.


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## PromptCritical (Feb 19, 2009)

Lowers the pressure locally from accelerating the water around the impellar and allows boiling at low temperature. My power head has started doing this when I first start it up. Cavitation is big deal on a submarine, by the way.


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## FlyHigh (Nov 15, 2009)

From Wikipedia:

"Discharge cavitation occurs when the pump discharge pressure is extremely high, normally occurring in a pump that is running at less than 10% of its best efficiency point. The high discharge pressure causes the majority of the fluid to circulate inside the pump instead of being allowed to flow out the discharge. As the liquid flows around the impeller, it must pass through the small clearance between the impeller and the pump housing at extremely high velocity. This velocity causes a vacuum to develop at the housing wall (similar to what occurs in a venturi), which turns the liquid into a vapor. A pump that has been operating under these conditions shows premature wear of the impeller vane tips and the pump housing. In addition, due to the high pressure conditions, premature failure of the pump's mechanical seal and bearings can be expected. Under extreme conditions, this can break the impeller shaft."

Interesting. I think I'm going to go clean my filters now :lol:


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## cichlidpastor (Jun 20, 2009)

thanks for all that info. I took both powerheads apart and they were both really clean. I put them back together and tey still blow the bubbles. This is irritating me. Thanks for the wikipedia flyhigh, still trying to digest it. :-?


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## JWerner2 (Jul 7, 2008)

Lube the impeller with some Vaseline. Thats what I do to stop cavitation of this type as well as make sure its clean of debris or the pre filter media is not to clogged up.


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## FlyHigh (Nov 15, 2009)

before he does that, are we really sure these bubbles are from cavitation? If everything looked clean to him, maybe there is another cause before he puts Vaseline into his powerhead? I don't know, that seems extreme to me but that may be a common practice.


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## JWerner2 (Jul 7, 2008)

Its very common practice. This is the same place I got the idea from for the same type of problem over a year ago.


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## cichlidpastor (Jun 20, 2009)

I am inclined to think that its not the powerheads for the following reasons:

1. They are both blowing bubbles and they started at the same time. I find it hard to believe they developed the same problem simultaneously.

2. It started when I removed my Emp 400 from that side of the tank. I had 2 on each side and had the powerheads positioned in the corner of one side just to the left of the HOB. (I set up a new tank and needed a seasoned filter, a new Emp is coming tomorrow to replace it).

Could taking the HOB out have something to do with it? Sounds odd, but it's the only thing that changed.


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## cichlidpastor (Jun 20, 2009)

Okay my new Emperor 400 came in to replace the one I put on the new tank. I put it on and started it up and then turned on my powerheads (both are mounted next to the new filter) and what do you know, they stopped blowing bubbles, they are running clear and smooth. How can this be?


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## KaiserSousay (Nov 2, 2008)

Man oh man,
That is one spooky deal.
Have not a clue about the bubbles, but know, I would not do anything to get that tank mad at me.
If you start having dreams involving the sacrifice of small animals, in front of a huge fish tankÃ¢â‚¬Â¦
Get out of the house, quickly.


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