Eheim 1260 micro bubble issue - help w/ troubleshooting needed

[IPT]

I am running an Eheim 1260 return (two seperate tanks, same problem, same model pump being used). They are plumbed themsame and both have a microbubble issue. I am at a loss. I cannot believe I have a pinhole leak in two seperate systems. I also don't believe it's a pinhope leak because of the bubble pattern. There is a light steady stream of bubbles (could be a leak, butr I don't think so) but what gets me is the burst of increased bubbles every min or so.

Here's the relevant info. Eheim 1260 output using 1" fitting into Flex PVC. Through a union and then into a WavySea (both systems). Pump intake is stock, under 6+ inches of non turbulent water, and unobstructed. It's been running 4 weeks now so there should be some slime built up in it.

Aside from air being sucked into the pumps intake what could cause this? I am open to all and any suggestions or ideas. Just make it stop :)!

[chris4869]

Clogged intake will cause it too, but you had already check that. Are you using the foam? If so, try removing it.

[jmait769]

I too just added an Eheim 1260 on my system about six weeks ago and experienced same issue. I replaced a QO 3000 with the Eheim. I had absolutely no micro bubble issues with the QO it just wouldn’t restart reliably. I used the exact same plumbing (1.25 PVC, split into two outlets) and I could not understand why they were being created. I noticed that the Eheim was putting out a lot more flow than the QO so I diverted some of the water using a T above the pump back into the sump to match as close as I could to what I had before and the bubbles have diminished. I’m not using the foam and the water around the pump is in non turbulent water as well. If I run it wide open I get the steady stream of bubbles.

Jay

[lhoy]

Do you have a Gate Valve plumbed in above the pump so you can throttle back the output? I have that on my PanWorld pump for my 225 and I was able to totally remove any microbubbles by throttling back the pump a bit.

Lee

[chris4869]

I would pull the pump apart and inspect the round pump cover. I'm not talking about the outer square plastice intake screen.

I have a feeling you either have sand or snail shell blocking the the inlet.

[Wryknow]

You know, not that long ago I started getting some micro-bubbles in my system which has vexed me a bit. I assumed that must have a leak in the return plumbing or something but I read this, figured "what the heck its worth a try" and took the foam out of my 1262. The bubbles went away completely in less than an hour! What I can't put my mind around is why the %&^(*% heck did this work? My return pump is under 12" of water in the sump. How did the foam over the intake cause micro bubbles????? Can anyone explain this to me?

[miwoodar]

I think it has to do with the low pressure on the intake side. If you reduce the pressure enough the water will literally boil into a vapor. You can induce boiling by undersizing the intake piping or by placing a restriction over the intake.

Here's an example:
http://www.physics.montana.edu/demonstrations/video/4_thermodynamics/demos/boilwaterunderreducedpressure.html