Sooooo aggrevating!!!

[Conesus_Kid]

I had been experiencing some microbubbles in the display, and could find no reason in the sump why I would be getting them.

As per the advice on this forum, I took the sump offline and gooped both sides of every joint from the return pump to the display. I waited the recommended 24 hours, did a 20 gallon water change, and put the sump back online.

Guess what? I still am getting the microbubbles.

I don't see any bubbles entering the return pump (submerged Ocean Runner 6500). The bubbles aren't constant. I get a "pulse" every 30 seconds or so.

Could this be something with the pump? It's relatively new (~3 months old).

I'm at a loss here...

Any ideas? I'm grasping at straws now.

[PCIALF]

If it is like clockwork (every 30 sec.) I would look at the pump. Can you test with a different pump and eliminate or convict it?

[jjjo]

sounds like air is getting in. is there a "whooosh" sound before the bubbles? when my sump water level is too low, it makes a "woosh" sound and then bubbles everywhere.

either your sump is low, or there is a leak in the plumbing somwhere.

put a light behind sump. if you put light in front, you wont see the bubbles entering the pump.

reduce water flow may also help. or add baffles

[jjjo]

could also be a small crack in the plumbing somwhere

[redrider911]

Or a big air pocket in the plumbing somewhere. Can you give things a shake?

[Conesus_Kid]

I've got my old Mag 5 laying around. I'll give that a try after Christmas. Could a pump produce the bubbles if no air is entering the system (cavitation)?

I have baffles and an ATO, so my water level stays constant. There's no sound associated with the pulse of microbubbles.

There's a light next to the return over the fuge, which illuminates the whole sump.

All of the plumbing is spa flex, so if there was a crack, it would be in one of the 45's or Tee's.

I'll post up some pics if I get a chance later.

Thanks for the ideas (and keep them coming)!

Off to the outlaws for a Christmas party now.

[ElDiabloPollo]

A pump can cavitate, but that generally only occurs when you restrict the input.

[chuckh]

one of my power heads does that. like every 30 seconds spits out air bubbles, no idea why. its not getting air because it fully submerged. try and look at the powerheads and see

[Gary Majchrzak]

Originally posted by ElDiabloPollo
A pump can cavitate, but that generally only occurs when you restrict the input.

a pump can also cavitate if the water pressure feeding it isn't enough. How far below the water surface is your pump's intake, Conesus?

Did you remove the hose connection and install the filter basket?

http://www.customaquatic.com/customa...ceanrunner.pdf

[Conesus_Kid]

I've got the filter basket installed, and it's under about 12" of water.

Would this be on the low end of input pressure?

[PCIALF]

how high is this pumping

[SkiFletch]

Originally posted by Conesus_Kid
I've got the filter basket installed

That's very telling if you ask me. Filter baskets can be very restrictive on the inlet flow of a pump, especially if they're not very clean. And as mentioned, restricted inlets leads to exceptionally high negative pressures inside the impeller housing. So low that gasses are ripped out of solution (cavitation).

Anyway you can get a pic up of the inlet housing?

[acdraindrps]

A pump can cavitate, but that generally only occurs when you restrict the input.

Thats what I was thinking....

[bjromaine]

For a pump to caviate, it has to get air from somewhere.
Either a leak, the sump is low or the drain from the tank is not keeping up with the return from the pump.
Also what Gary said is possible. The pump needs to be low enough in the water (sump) that it is not creating a vortex from the pump intake and getting air from that.
You might have to eliminate one thing at a time starting the furthest from the return in the tank, namely the pump.

Do you have a hole in the return for anti-siphoning? Could it be above the water line?

Hope you find it, good luck.

[ElDiabloPollo]

Actually, cavitation causes the water to change state into vapor hence the micro bubbles.

[Conesus_Kid]

Originally posted by SkiFletch
And as mentioned, restricted inlets leads to exceptionally high negative pressures inside the impeller housing. So low that gasses are ripped out of solution (cavitation).

Ahh, that's what I couldn't remember: the part about gases being stripped out of solution. I'm betting that's the culprit since this developed over time.

I'll take of the filter basket tomorrow. Dollars to donuts says it's crapped up pretty well.

Cross your fingers!!!

Thanks!

[Gary Majchrzak]

bingo.
I won't take you up on that bet. I can't see myself giving up any donuts!

[cardiffgiant]

Tagging along because I'm still getting a few m bubbles in my display.

I gooped the return plumbing really well, but still got some. It's much better after getting more volume into the return chamber (and reworking things so that a power failure won't put a ton of water on my floor).

I'm going to try taking the sponge and filter basket off of the mag 5 return. I don't think I need it any way, with the filter sock on the feed from the display.

[Conesus_Kid]

No more filterbasket= no more microbubbles

Thanks for all the help, gang!

[cardiffgiant]

Nice!

[thriceanangel]

And it would have gotten away with it too if it wasn't for those meddling kids!