MAG 18 making buzzing sound

[dow]

Well, I finally got the tank plumbed today, and it's filled and the mag 18 is running on the closed loop. I'll be running a leak test probably for the coming week, and then I'm planning to swap tanks this coming weekend.

One thing that I noticed though, is that when the mag 18 is running wide open, it makes a hissing-buzzing sound. I can turn the ball valve down on the output side of the pump and the sound goes away, but so does a lot of my water movement. Does anybody know what could be causing this, and how to make the sound either go away or make it less noticeable?

A relatively fast solution would be great, Beth has already asked about it three or four times, and she's only been around it for about an hour.

Thanks!

[NaCl_H2O]

Where is the pump in relation to the water level in the tank? Some head pressure may eliminate the noise?

[aquadoc]

What size pipe are you using? 3/4'' or 1''.

[Tim Marvin]

Mags always vibrate. Is it sitting on something or haging by the pipes? You can place some felt or rubber under it and that should help if it is sitting on a shelf or on the stand.

[MikeDeL]

Mags always vibrate. Is it sitting on something or haging by the pipes? You can place some felt or rubber under it and that should help if it is sitting on a shelf or on the stand.

This was my first thought too. Even if one of the pipes isnt hanging, if it is touching something it will make a vibrating noise.

[dow]

NaCl_H2O: It's sitting on foam rubber even with the bottom of my tank, and immediately behind it. The inlet from the tank for the closed loop is about 14" up from the bottom, and the tank is 24" tall.

aquadoc: Inlet is 1-1/2"spaflex to an ell and reducing to 3/4" through a ball valve and a union to the pump. Outlet is 3/4" union and ball valve then to 1-1/2" spaflex rising up to a 3/4" return manifold with four 3/4" tees into the tank.

Tim: It's sitting lightly on the foam pad that came with the pump, with probably half of the weight being supported by the lines.

ALL: This isn't so much of a vibration type sound, but more of a hissing-buzzing sound. It sounds almost as if there is air getting into the lines, but there is none coming out, and water flow is very good.

Any further thoughts? I wish I could provide some pictures, but my digital camera is still AWOL in a box somewhere.

[MikeDeL]

Are there any micro bubbles coming out? maybe the impeller is loose or bad. Is this a new pump?

[dow]

Are there any micro bubbles coming out? maybe the impeller is loose or bad. Is this a new pump?

Brand new pump. I used it to drain the tank (submerged) after the initial leak test to make sure the silicone didn't leak, and that's it. I don't see any microbubbles coming out anywhere.

[oceancube]

Mags always vibrate. Is it sitting on something or haging by the pipes? You can place some felt or rubber under it and that should help if it is sitting on a shelf or on the stand.well tim said it best, i noticed my mag 9.5 did the same, after putting a piece of filterfloss under it , all the buzzing was gone, try insulating the bottom of it with some type of soft material!!!

[starboard]

Your absolutely sure it is coming from the pump?

[dow]

Your absolutely sure it is coming from the pump?

About 99% sure. There's nothing else hooked up to the tank at this time. The only water movement right now is the closed loop.

[dow]

Mags always vibrate. Is it sitting on something or haging by the pipes? You can place some felt or rubber under it and that should help if it is sitting on a shelf or on the stand.well tim said it best, i noticed my mag 9.5 did the same, after putting a piece of filterfloss under it , all the buzzing was gone, try insulating the bottom of it with some type of soft material!!!

I hear it even if I hold the thing in my hand and it's not touching anything. This isn't a "vibrating against the shelf/tank bottom/tank wall thing, it seems to be internal to the pump.

[starboard]

I'm wondering if it is the impeller also. Does it make any difference if you slightly lift the pump with your hands while it is running?

[MikeDeL]

Can you take it apart? Maybe something got sucked up in there.

[starboard]

Good thought, did you use teflon tape? It could have a strand rubbing on the impeller making noise.

[NaCl_H2O]

You said the noise quits if you load down the pump (close down the ball valve). I think that means that it is impeller noise you are hearing. I would take it apart and inspect the impeller, shaft, and housing. I had a brand new Mag12 Impeller with a defect (Large chip) in the magnet.

But, Mags are fairly noisy pumps. Lowering the pump down to floor level might change/eliminate the noise due to head pressure?

[dow]

Well, I tore the pump down, and there was some flash left over from when they made the impellor. Trimmed it off, and smoothed things up as well as I could and put it back on. It's still doing it, but it's better. The buzz almost completely goes away if I shut the ball valve by about half. Tomorrow, I might break it down again and look closer. By the way, there's a rubber blade that's installed in the cover and points toward the outlet side. Any idea what that thing does?

[Dozer]

My first thought would also be vibration- maybe not the pump itself, but some hard pvc vibrating against the tank or something? Or did you use all flex tube on it?

Assuming it's not that, then it's either the pump or your plumbing I guess. Is there any way you can use your bathtub (or pond if you have one) and do some quick testing with it? Run it underwater and see how it performs. Then, hook up a really short, simple piece of tubing from the tub/pond to the inlet, with the pump in your hand outside the water, and see how that works. Do you know what I mean? Try to experiment with it with as little plumbing as possible and it will help you to isolate if the pump is the problem or your plumbing. The first closed loop I ever built was with a Mag 9.5, and I had a hell of a time with it. It was a real pain to get it primed and keep it from cavitating. Granted, later I realized I hadn't built it very well, so it wasn't all the Mag's fault, but when I got a PanWorld and hooked it up to the same CL plumbing it worked fine (although I did go back and replumb later anyway to make it better).

[dow]

I just talked to Val at Danner manufacturing, makers of the Mag pumps. She said that it sounds like it's cavitating, and that the way I have it plumbed sounds ok, so she's sending me a new cover and impellor to see if that will help with it.

As a note, she also said that if the inlet isn't as large as the outlet side, that sometimes you can "starve the impellor" and get "impellor chatter."

I'll post back when I know more.

[Tim Marvin]

Hmmm, it seems to me the inlet and outlet are the same size due to the pump housing construction...

[Polkster13]

I think she may have been talking about the plumbing to the pump and not the pump itself. You can have a 2 inch inlet on the pump but if you put a 1.5 to 2 inch reducer on the intake, then the pump would not be getting the amount of water flow for which it had been designed.

[dow]

I think she may have been talking about the plumbing to the pump and not the pump itself.

Yep, that's what she was talking about. She also told me that if you're only talking less than 6" or so from the pump to the larger line, that it shouldn't have any impact, but if you're talking a longer run, then it could cause problems.

[Dozer]

Yep, you're having the same problem I did with a Mag on a closed loop. I never really could stop the chatter sufficiently so I sent it back and went with a good external magnetic driven pump. I found I could get a PanWorld for not much more than say a Mag18, and it seemed so much better for an external application. Also, I don't want to speak for anyone, but check with NaCl, I believe I read where he started with Mags and converted to PanWorlds for closed loops. Also, I have heard/read that Mags overrate their return flow rates, so don't necessarily be scared off when comparing an Iwaki or Panworld type pump that's rated only around 1000-1300gph to a Mag that's rated at 1800gph. In the actual application they may actually put out just as much or more. I'll let the physics/engineer types try to explain why- or the guys that have been doing this a long time. I was in your exact situation and someone on this board- I think it was Joshua- swore to me that a PanWorld rated at 1270gph would outperform an old Mag 18 I had- and he turned out to be right...

Btw, I'm thinking about selling the PanWorld I was just talking about to upgrade to a Tunze or Sequence pump. The PanWorld works great but I'm thinking I want more flow. Hope this doesn't sound like a sales job, honestly there are several people who I know would take it so I'm not trying to push it on you! But it is a great pump for a closed loop if you're interested let me know.

[NaCl_H2O]

... but check with NaCl, I believe I read where he started with Mags and converted to PanWorlds for closed loops.

Yup, I tried to use Mag5 & 7s for closed loops (don't compare to the MAG 12 or 18s. The small MAGs were cavetating badly and causing bubbles.

Al that aside, I use the MAG12s for other portions of my system and I am relatively happy with them, but will eventualy replace with PWs.

Panworld/Iwaki/Blueline are no doubt far superior pumps to MAGs. They do provide flow closer to their advertised specs, and from my experience, the MAGs produce far less flow than their specs given ANY head pressure.

[eric]

I think you have a cavitation issue, not in the pump but one of the PVC fixtures. Guess somewhere between the elbow and the inlet of the pump. Lower pressure or increased flow rate will cause a cavitation.

Any change if you close the inlet valve a little bit? Not too much.

I wonder...Something you could try, since your bulkhead is low enough to allow you to have a wide water level range. With just that loop running and both valves fully open see if the noise differs between a water level just above the bulkhead and the water level kept at the top of the tank. I'm not sure that raising the water level would increase the pressure or not. It's just something I would try if I were having the problem. Doesn't really provide any solution, but might show you're cavitating if the noise lowers if the water level is raised.

And then hmmm, I think someone suggested some eductors on the discharge of the manifold. Would that produce a similar back pressure like closing the valve?

[PsychFish13]

mousepads are awesome insulators for noise and vibration