How does one eliminate microbubbles?

[magdelan]

I am litterally at wits-end here. I have reconfigured my sump to pump plumbing 5 times now and continue to get microbubbles in my display. I even have the bulkhead inside the sump capped with a filter which is covered with sponge to catch any micro bubbles comming out of the bubble-trap.

I am also using a different pump than I had origionally started with just to rule out the pump as a potential source.

The water exits the sump through a bulkhead, flows through a hose adapter, through one inch vinal tubing, back into a hose adapter, through rounded 90 degree elbow and into the pump. It is here, at THIS point, that I can hear an intermitent *swish* noise in the pump. It was the same on the other pump aswell. Everything is sealed well (although there is a tiny drip on the underneath part of the pump, but I don't believe this is the source). After the water leaves the pump, it goes through two wyes. The one on the left has two hose adapters on it which go to the two back returns. The wye on the right is hard plumbed to the right side return.

I do NOT believe that there is anything wrong in the plumbing after the pump because all three drains individually spit microbubbles. I believe that the problem is occuring inside the pump...AND I DON'T KNOW WHY!!!!!!!!!! :uzi: Please help!

 

[JGarcia9102]

This is a long shot, but do you have any other powerheads running in the display that could cause bubbles? I had a large aquaclear running at one point that was positioned in a way that trapped bubbles in the output and filled my tank... just a thought.

 

[magdelan]

I only have one koralia in there right now, but all three returns are producing bubbles. Thanks though.... I'll entertain just about any suggestion right about now. Maybe my ceiling fan is spinning too fast :hmm4:

 

[tmz]

Sounds like with the bubble trap and filter on the pump you are probably not adding air via bubbles to the water going through the pump. The drip make be a small leak which can act like a venturi ,ie, suck in air as the water moves through.

 

[mr.maroonsalty]

i agree with Tom, and would want to track down that leak; I've seen plumbers try to fix pvc fitting leaks by painting around the connection with their glue, since it must be happening in the small length of plumbing all three branches share it should be easier eliminating a venturi.

 

[Kent D.]

What micron sock filter are you using?

 

[porpoiseaquatic]

I'd suspect that you've got a small air leak between the tank and the pump. Small enough to draw air in but not large enough to leak as long as the pump is running. Trying shutting the pump off for a few minutes and see if any water drops form on the outside of the plumbing. Another place is around the pump volute (impeller cover). These sometimes warp and bring air in but again, as long as water is moving...they don't leak. I'd go after the plumbing leak though as that is more likely the culprit.

 

[pascal32]

Tom's suggestion on a venturi is a strong possibility. I have heard of cases where there was a leak that only showed when the pump was off - the water flow was sucking in air.

In addition you could be generating micro bubbles on the drain line - even through the filter sock. I had to DOUBLE sock with the felt (thick fuzzy) socks, the mesh ones didn't help.

shining a bright flashlight into the sump you should be able to see the micro bubbles

couple notes:
* When I first set up my 120 I had a 200 micron sock and a triple baffle in my sump and was still blowing through micro bubbles because of the drain line. I DOUBLE sock the return and all is well now
* with micro bubbles it takes a while to go away, you need to let things run for a few hours before they start to get better
* ideally you should not have 90 degree bends in front of the return pump, they restrict flow which is bad for the pump
* Those are some big PVC pipes coming off the return pump with a lot of fittings - is there a reason for the size selection? You might get better flow with splitting three way at the pump and running flex the rest of the way - though i doubt that is adding to the bubbles.

 

[RyanEG]

Im going to suspect that your pump is cavatating with that 90 so close to the intake portion of the impeller.

 

[suppressivefire]

I agree with Ryan and I run a 25 micron to help with micro bubbles when I ran a 100 micron it didn't help at all. Good luck!

 

[magdelan]

Blurry- very helpful, thank you.

Ryan- The 90 degree angle has been the only constant. You may be right.


I'll take it all into considderation.

 

[Johnsy85]

If you are cavitating your pump, you may be able to stop that by increasing the level in your sump (as long as you still have the volume for any power loss).

I had some issues with micro bubbles in my tank and I noticed that once every 10 minutes I would suck in a very small bubble into my pump and that was all that it took. I raised the level in my sump and a slime coat developed and I have been clear ever since.

 

[Conesus_Kid]

I'm with Ryan. Also, the filter sponge you have on the pump intake can cause cavitation if it starts to plug up and restrict flow to the pump.

I get microbubbles on my closed loop when the intake gets partially blocked with collinista snails.

Try pulling off the sponge, cover up one of the outlets in the tank to purge the air out of the system, and see what happens.

If there's a drip coming from the pump, it may be pulling air in, but it sounds like you're getting lots a bubbles and is most likely a cavitation problem.

 

[magdelan]

Just replumbed for the 5th time. I still have micro bubbles. I think that there is a small small small small small separation between the white impeller cover and the blue metal case. I'm going to let it go for the week and see if it fixes itself, otherwise I'm going to try a ring of silicone between the two.

 

[captain7359]

Try a sock on the overflow line into the sump and skimmer outlet. If the oring is seated and sealed well at the pump housing it shouldn't leak. A thin coating of vaseline on the oring should assure a good seal. I wouldn't worry about the 90 creating cavitation as all our aquarium pumps are too small to create cavitation. How did the water flow through the baffles? Was it over the first under the second or under the first over the second? I've used a piece of foam between the baffles before to separate out the small bubbles.

 

[magdelan]

It's all a mystery, Walter. I don't know what else to do. And the water in the sump goes over under over. Right now I have three carbon pads between the skimmer-side baffle and middle baffle.

 

[Conesus_Kid]

Can you see any bubbles entering the pipe that feeds the pump?

If not, my vote goes to either: 1) a pin hole air leak, or 2) pump cavitation.

Did you try removing the filter sponge you have over the inlet?

 

[magdelan]

The filter sponge has been removed and I've tried shining a light through the vinal tubing that goes from the sump to the pump, but I can't see any bubbles. I'm wondering if there are bubbles and the water is just moving way to fast for me to see them. I can now hear a constant fizzle in the impeller housing to the pump so I am guessing that it is a pin hole leak. I have bought some silicone that I am going to reseal the pump with.

This is how I have my plumbing configued *today*.

After taking this picture, you can see the water turbulance occuring after the baffle. I have raised the water level in the sump to prevent the turbulance however, in the event of a power outage, my sump will overflow for sure....not good.

 

[captain7359]

I'm wondering if there are bubbles and the water is just moving way to fast for me to see them.

Most likely they are moving too fast

After taking this picture, you can see the water turbulance occuring after the baffle. I have raised the water level in the sump to prevent the turbulance however, in the event of a power outage, my sump will overflow for sure....not good.

That baffle is making a ton of bubbles for you :sad2:

Have you shut off all the power and filled the sump to the brim to see how high you can run the water level?

Put that spare piece of glass from the other baffle at the edge of the last baffle on an angle to let the water slide down the sloped glass instead of crasing into the water to try and cut down bubbles??

 

[Johnsy85]

I am guessing that some of those small bubbles get sucked into your pump, smashed into smaller bubbles and then pumped into your tank.

Raising the level in the last chamber will help to decrease those bubbles, but you have to leave room for power outages ><.