Closed loop micro bubbles

[Anonymous]

I have a hammerhead driving a double alternating manifold using an OM 4-way. Each half of the manifold has 5 outlets that run down to the water using loc-lines. I'm having a lot of microbubbles. There's no leaks anywhere. Could the loc-lines be leaking air in?

Not sure if this matters, but a detail in the system: The exit to the loop goes over the back, and I have a T junction there with a screw plug, so I could unscrew it an pump water in to easily prime. That same configuration caused cavitation in my skimmer pump and I had to take it out, But it seems like the hammerhead should have no trouble keeping that cavity full of water.

 

[Anonymous]

You can have a leak on the intake side of the closed loop and you will not see any water come out, but air will get in. I had that problem, I kept tightning things until I got rid of the bubbles.

Also, I understand exactly what you are saying about the T with the plug. That my cause microbubbles for a while until most of the air is sucked out of that cavity. Is there anyway you could cover or tape off the intake and outlet s and take the plug out and fill it all the way up to the very top?

Hope that helped....

 

[Anonymous]

Could the loc-lines be leaking air in?

I don't think so.

There could still be cavitation at the impeller since the pump is so strong. An easy way to test for impeller cavitation is to restrict the output slightly. If the bubbles go away then that's probably it.

The solution is to get water to the pump more efficiently or restrict the output a little.

I assume you want all of the output possible so fixing the input is the only option. If it has a 1.5" intake and you added a couple/few elbows from the intake to the pump then you have restricted the input. What you have to do then is use 2" plumbing (whatever is larger than the intake to the pump) all the way to the intake. This will lessen the restriction on the elbows and hopefully get water to the pump more efficiently.

 

[Anonymous]

Thanks guys. I'm going to try closing down the output a little and see if that helps.

 

[Anonymous]

I set the ball valve before the return manifold to about a 45 degree angle, enough to noticably slow down the flow. No reduction in bubbles, even the following morning.

:?

 

[Anonymous]

Dang. It points to what Knucklehead said then. A pinhole leak somewhere along the intake. Those are a pain to track down. Is all of the plumbing along the intake glued?

 

[Anonymous]

Yep. Except for that T union that occurs when it goes over the top, which has a screw-in plug. I taped a plastic bag over the whole thing, so it seems there is no problem with that....

 

[Anonymous]

I'm out of ideas. Sorry.

 

[Anonymous]

I'll just screw the pump on backwards and see where the water shoots out of! :lol:

I guess I'll just go over the outside of the glued joints with plumbers goop or something. Thanks for the help Guy.

 

[Anonymous]

Glued joints can just get a small dose of the normal pvc glue around the outside with a q-tip

That sometimes does the trick...

 

[Anonymous]

Yep. Except for that T union that occurs when it goes over the top, which has a screw-in plug. I taped a plastic bag over the whole thing, so it seems there is no problem with that....

That T union is on the Intake side?

Taping a plastic bag over it would not stop your leak, unless you can tape it airtight which would be very hard.

I would start by making sure the threads are wrapped with teflon tape correctly and then make it hand tight plus one quarter turn with a wrench.

Then tighten it some more if that doesn't stop the bubbles.

If it got so tight that I was afraid it was going to break I would then start looking for leaks other places.





one other thing I had a problem with, I had another return pump dumping back in the tank right close to the intake of my closed loop. When I shut that off I had less bubbles, and it turned out that I was blowing bubbles right into the intake of the closed loop.


Yeah, I had tons of bubble problems..... :lol:

 

[Anonymous]

I figured the bag would at least collapse if there was negative pressure inside it, but I guess if it was slow enough maybe not. I still think its a airtight because I've opened it a couple times in the past and I have to unscrew it almost all the way before I hear air rush in and the water fall out of the tube into the tank...

I think I'll try your q-tip trick.

 

[Anonymous]

Cool word: cavitation . I did a "define: cavitation" on google. 8)

~wings~

 

[Anonymous]

Any results?



I have another one to check if that wasn't it.

IF your return pump has a cover over the impeller or some other way to take it apart, make sure any gaskets are set right, and all screws or bolts are tight....

And that is it, I am totally out of idears....

 

[Anonymous]

Nah, been busy at school. Hopefully over the weekend. Its a big honkin sequence pump. Not sure I'm about to dissassemble it...

 

[Anonymous]

No need to disassemble it.

Just make sure everything is tight....

 

[Anonymous]

I just looked at some sequence pumps.

Some of them do not come with saltwater seals, not sure which one you have.

The other thing is the impellor housing is surrounded by bolts. Those are the ones that need to be tight.

Good luck

 

[Anonymous]

The hammerheads are made for marine aquaria, I believe. I'll check for tightness...

 

[reefkeep1]

Dan:

I have a Sequence Hammerhead and have had bubble problems ever since set up as my return pump. I'm not yet blaming the pump until I investigate all potential causes. My two overflows return to a sump, and when the water falls into the sump I get a lot of microbubbles and some foam. I have yet to tinker with that setup to see if it changes the amount of bubbles in the tank. When I turn a ballvalve on the outtake side it decreases flow and decreases bubbles, but I'd prefer to have higher flow. I have some salt creep on the 1.5" pvc running back to the tank, but have not found any leaks on the intake side (from the sump to the pump).

RK1

 

[Anonymous]

Well, I think mine is cavitation. I closed down the valve on the return more severely and pretty much eliminated the bubbles. Crap.

I have 1.5 inch line with a T to 2 intake strainers inside the tank, and a T (and 90) over the back. Its flexible pvc probably about 6 feet to the pump just under the floor. Also right before the pump I put a true union release. These guys reduce flow a lot, so I usually upsize them and put in a reducer bushing, but for whatever reason I didn't this time.

That trick with the T over the back (just for easy priming) caused my skimmer such grief (so much cavitation that it wouldn't even be able to get up a good head of steam) that I wouldn't be surprised if that config is the culprit too. I have no understanding of whay that config is a problem though.

Guess I'll order some 2" black pvc and a big strainer tomorrow.

I've been running the thing with micro bubbles for 10 days probably. Any ideas on how fast the pump could be damaged?