A Ton of Microbubbles

[thresher9]

There are millions of microbubbles in my tank constantly and I have no clue where they're coming from. I just added a skimmer and the bubble where there long before I did so it is not that. I have a bubble trap in my sump, but obviously it's not doing its job. The return pump is submerged in the water, so I think it's making them. Any ideas?

 

[bang guy]

Quote:
Originally Posted by thresher9 http:///t/396904/a-ton-of-microbubbles#post_3536292
There are millions of microbubbles in my tank constantly and I have no clue where they're coming from. I just added a skimmer and the bubble where there long before I did so it is not that. I have a bubble trap in my sump, but obviously it's not doing its job. The return pump is submerged in the water, so I think it's making them. Any ideas?

To determine if it's the water pump you need to restrict the flow from the pump. If the bubbles decrease when you restrict the output side then it's the pump in the form of cavitation.

 

[thresher9]

Is there an easy way to restrict the flow? The return is only the pump with one line dropping back into the display tank. And how would I get rid of any air trapped in the pump?

 

[bang guy]

I don't think you have any air trapped in your pump. I would think it would all blow out as soon as you start it.

If you provide a picture of your return I might be able to suggest an easy way to restrict the flow. Is the return line rigid or flexible?

I have a concern based on your description. Have you tested to see what happens to the tank water when you unplug the pump?

 

[saxman]

Bang asked some very pertinent questions. Here are a couple of other thoughts/questions:

Are any of your connections to the pump exposed to the air? There may be an air leak.

Also, if there are bubbles coming past the bubble trap, they'll be shredded by the pump's impeller. Sometimes you need to turn the pump intake away from the final baffle if its an "over" flow baffle.

Are you running a skimmer?

 

[thresher9]

Here are some pictures. I've tested many times what happens when the pump is turned off since I live what the power goes out all the time. The return back siphons until it's out of the water. If the powerbeads are off the water looks like gel with all the bubbles suspended. I am running a skimmer, but it's not whats making the bubbles. In the sump the last baffle before the pump has the water flowing under, acting kind of like a second bubble trap.

 

[beaslbob]

just a wild guess here but it looks like the return line is a small diameter.
I would first try the largest diameter you can get like at least 1 1/2 inch diameter rigid. pvc.
I think you will find that will also increase the flow through the system.
my .02

 

[bang guy]

Quote:
Originally Posted by thresher9 http:///t/396904/a-ton-of-microbubbles#post_3536334
Here are some pictures. I've tested many times what happens when the pump is turned off since I live what the power goes out all the time. The return back siphons until it's out of the water. If the powerbeads are off the water looks like gel with all the bubbles suspended. I am running a skimmer, but it's not whats making the bubbles. In the sump the last baffle before the pump has the water flowing under, acting kind of like a second bubble trap.



OK, so the return looks flexible. To restrict the out put just put a pair of vise grips on it to cut the flow 25% or so. If the bubbles stop then it's cavitation. If the bubbles continue then somehow bubbles are getting through your bubble traps.

Cavitation can be cause by a few things. The most common are a clogged prefilter, unsufficient intake, or a damaged impeller.

 

[thresher9]

The pump is new so I doubt the impeller is damaged or maybe it came damaged and I cleaned the pump's pre filter, there wasn't much there. I'll try the vise grips, good idea.

 

[saxman]

Since you mentioned power outages and the fact that your return line "goes dry" when the back-siphoning from the DT stops, I have to wonder if there is air in the pump, which gets shredded and sent to the DT upon power-up, and once the bubbles are in the water, they tend to keep running thru the pump and self-propagating to some degree thereafter.

I'd definitely look into the cavitation scenario as well, and since you used flex tubing, it would be an easy job to add a valve between the pump and the DT to tune the flow. Likewise, and altho I really don't recommend them in most cases, a check valve will keep the air out of your pump, which might be the issue, as mentioned.

If you do end up with a check valve, get one of the flapper-type or ball type that have no metal or springs. They also make them with clear bodies and access lids for inspection/cleaning...don't go cheap on this fitting if you use one.