Microbubbles....grrrrr.

S

Sherita

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Ok, someone help me figure this out, because I am STUMPED. Tank in question is 72g, plumbing is mag10 return, plumbed in with 1"pvc. There is no closed loop or sqwd on this tank, I do have two MJ1000's running on a wavemaker, but they are completely underwater. For the last three weeks I have had microbubbles in my DT. At first I assumed the pump was picking them up from the sump (3 chambered sump with bubble traps, set up as skimmer>return>fuge), so I re-routed the intake of the pump in case it was picking up air from the fuge overflow and I could not see it. Still had bubbles. Put a new foam cover over the intake, still had bubbles. Removed the foam cover and replaced with a piece of pvc routed to a very obvious bubble free area, yet still had bubbles. I then shut the system down, plugged the return outlets and pressure tested to 60 lbs. Pressure held with no loss for over an hour. Pulled the pump, put it in a water barrel and ran it. No bubbles. I has suspected that there was a tiny leak, allowing the fast moving water to suck air in, but the pressure test blew that theory. I give up. Where are these dang bubbles coming from? The return pump is submerged well below the water line, no fittings are leaking, and all locline is submerged and unable to suck air. If anyone has ANY ideas, I would love to hear them. My next step is going to be to pull the plumbing and replumb using spaflex, if I can find any locally (nearest Home Depot does not have it, I live in the boonies). Oh, I should mention that I have changed nothing in this tank in the last three weeks. I don't get it. Either I am missing something, or air bubbles are smarter than I am (at this point I won't comment on that, since I have yet to banish them from my tank). Suggestions anyone?
 
So, the pump is not occasionally sucking air like they do when they are just a little too close to the top? I have a Mag 3 return through flexible tubing submerged 2 inches in the water. I bet a Mag 10 would have to be 4 or maybe 5 inches under water to keep from occasionally sucking a vortex of air. My Seio circulating pumps do that as well if too close to the top. But they might not do it but once or twice all day long. I am sure you have eliminated that possibility! Just a thought.
 
Thanks for the suggestion DFW. This pump is under 7" of water, so I don't think it can suck air from the surface, but just in case, I put an elbow on the intake pointing down. I can see the fine spray of bubbles coming from the return in the tank, it happens all day long. Had I not pressure tested, I would swear that there is a pinhole leak somewhere that is sucking air as the water flows past, but how can air get in but not get out during the pressure test? This is truly driving me batty.
 
Do you have anti-syphon holes drilled in your return line? And are they perhaps above the water line in the overflow? I had this problem and had to plug them and drill new ones an inch lower. They were acting like a Venturi sucking in air just before the locline.
 
Had not thought of that, I am at work now but I will certainly check when I get home (yes, I do have anti-siphon holes, and they are quite close to the surface, underwater but maybe.....). Thanks for the idea!

@Freshandsalty wrote:
 
depending on the age of the piping you generally need to give the piping time to slime over that will help reduce the microbubble problem. Also the recommend pipe size for the mag 9.5 is 1 1/4 inch piping. I dont think you need to redo the piping just give it sometime. running a filter sock on the overflow will help rid some of them too
 
Tank has been up for over 8 months, so I would think that the lines would be slimed over. This just started about three weeks ago, but I have changed nothing........so it makes no sense. I will get to the bottom of this, the bubbles irritate me, but some of my corals are flat out aggravated about it.

Edit to add: both of my overflow drains have reverse durso's on them and bubbletraps between them and the return section. I also have bubble towers in both drain sections. Last night I tried shutting down the skimmer and carbon reactor, in case somehow they were causing the issue. No luck, still have tiny bubbles. I have tried to eliminate everything I can think of, am now hoping the good people on this forum can help out by thinking of what I might have missed. I want to avoid a replumb if at all possible, it would be a nightmare.
 
I would say check the antisiphon holes to make sure they aren't clogged and check the plumbing for any pin holes in between the pipe conjecture or maybe any flex lines that may have gotten loose. I would go ahead and run a filter sock to kind of strain out the bubbles so that it won't look so bad until you find the issue.
 
Ok, I just checked my siphon holes, they are an inch below the surface and not obstructed. Just for giggles I extended the plumbing so that I could drop the pump into a bucket of still tankwater (obviously NO bubbles in there), guess what.......bubbles, everywhere. Possible pump issue?

Is it remotely possible that my pump is somehow cavitating and actually creating these little bubbles?

I re-tested the plumbing under 75psi this time, still no loss. I am just about to lose my mind here (what I have left of it anyway).
 
Ok, scratch the pump idea. I swapped out for my backup pump. Little bubbles every darn where. Sigh.
 
Pictures of your plumbing? There is a plumber that sponsors this site, I think. Plumber in the house?

David
 
Just to be clear, you ran your tank with two different pumps and got bubbles and you ran pump from a bubble free bucket of water and still have bubbles.

Do you have any couplings or removable rubber fittings?

When you pressure tested was that with air or water?

I have bubbles also so I am curious about what might be the same thing producing them.
 
Do you have a Fractionating Impeller on the pump?? Probably not but they sell a mag 9.5 with that. Sounds to me like you might be running to large a pump for your tank size and return. Are you running it full throttle? That pump is rated at 950 gph isnt it? Like said earlier use a filter sock and see what it does.
 
I forgot to ask. Since I'm running the same tank as you and same pump. First off the recommended pipe size on the mag 9.5 is 1 1/4 inch pipe I would gave thought that was the problem but since you have only recently suffered this issue might lead me to think the PVC to loc line might be leaking because mine did when I first setup my tank. Also another thing that happened to me is one of my loc line sections cracked sucking in air. I would check the loc if you adjusted it or anything that maybe an issue.
 
As far as I know, I do not have a fractionating impeller. Could I identify it by sight? What would it look like?

I got aggravated and switched the pump out for a mag 7 that I had laying around. Well, guess what....still got em. This is just crazy. When I did the pressure test it was done with air and a test gauge. Absolutely NO drop in pressure for over an hour. This makes no sense at all.

I have eliminated all locline, plugged all anti-siphon holes, put a filter sock on both drain lines, and wrapped the pump intake with filter floss. Still got bubbles. I even shut my MJ wavemakers off, in the event that somehow they had something to do with it. No change at all.

I guess the next step is to replumb with spaflex so I can eliminate as many joints as possible.

And sorry, but I can't get pictures of my plumbing, its all hidden behind the tank. It goes like this tho (starting from the pump in the sump). Pump/union/gatevalve/sweep 90/tee. From the tee, going to the left side of the tank>sweep 90(going up)sweep 90 (turn into tank)/45 (into water)45. Same on the right side of the tank. I did have locline dropping into the water, but I removed it trying to find the problem.

There is absolutely NO WAY that the pump is getting these bubbles from the sump. Sump is set up like so from left to right: drain and skimmer section/three baffle bubble trap>return>two baffle bubble trap/overflow/drain and refugium section. Both drains also have bubble towers on them, and reverse dursos with filter socks on them, live rock rubble in both bubble towers.

The problem has to be the piping. Somewhere. I am either getting cavitation in the pump or somewhere in the line. It's definitely not a leak, since I would have found that under pressure testing.

For the record, I hate stuff like this. I would rather have a busted line and water on the floor. At least that is easy to locate.
 
It is bubbles and not sand...right? Sounds like you about covered everything and you pretty much eliminated the mag 9 ocassianally sucking bubbles but did you try adding more SW to the sump so that the pump is deeper. May be worth it to at least totally rule it out. [smilie=smile.gif]

Cheers,
 
Is it possible that under pressure it shows no leaks, but under vacuum it might show a leak? Could it be leaking in, but not leaking out all at the same time?

David
 
bimmerzs, it's definitely bubbles, not sand. I did pour more water into the return section in case the pump was somehow sucking air from the surface, still got bubbles.

DFW, I hadn't thought of that, don't see how it could......BUT I can certainly pull a vacuum test on it to find out.

Keep the ideas coming folks, the bubbles will be banished yet!
 
"Keep the ideas coming folks, the bubbles will be banished yet!"

Yes they will!

David
 
OK, so changing the pump and raising the water level in the return do not change your bubbles. It would seem that by process of elimination you would then look at the return plumbing, which by the way is my next step also.

Spaflex is the flexible PVC pipe? Is there any way to test a different return line other than make the new return line?
 
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