Tunze 9012 impeller/foamer problem

[Clydester88]

Hello Roger,

I encountered many of the problems you've discussed with this skimmer.

In shipping, the peg under the foamer had snapped off and one of the clips that holds the foamer was twisted. I was able to glue both back into place so those are fine.

I now find that the skimmer won't always turn back on after it's been turned off. I know there's power going to the foamer but it's as if the impeller isn't seated properly or balanced properly. Also if I run the skimmer out of water, the impeller makes a loud rattling noise. When the skimmer is run submerged, it makes an initial loud rattle and then settles down and skims fine. It just doesn't reliably restart.

I'm in Canada and deal with Xenia for Tunze, and am unsure if I should order a replacement impeller or replace the entire foamer.

Any advice would be appreciated.

 

[rvitko]

I would try soaking the impeller in vinegar, I have seen calcium build up cement the needle wheel to the magnet eliminating the free play needed for the impeller to start moving. In general synchronous pumps require the magnet gets a running start before encountering the resistance of the impeller, most common AC pumps have about 270 degrees of free play between the impeller/propeller or needle wheel for this reason. If these parts cement together the motor has all the load of the water resistance and cannot start. It is also possible the impeller is failing but the cause may be simpler.

 

[Clydester88]

Thanks - I should have mentioned that it's a new skimmer. A replacement impeller is on it's way - hopefully that resolves it.

I also have an inordinate amount of bubbles coming out of one of the seams as well, but I understand that they should subside in time.

I do dose NO3PO4x as a carbon source - would that have any effect on the amount of microbubbles?

 

[rvitko]

If the bubbles come from one section I would be concerned that a part is not lined up right, the most overlooked is the intermediate plate interface with the bottom grid. The intermediate plate is the part the pump clips into, it has a tail that just touches the bottom grid with the holes in it. If that is too low it will cause a slight bulge where bubbles will escape. The intermediate plate will line up with grooves on the housing and so the very end just touches the bottom plate. I would expect the nitrate remover to increase stray bubbles, but if everything is assembled right and their is not a strong current from one side, I would expect those bubbles to emit evenly and not just from one small side section.

 

[Clydester88]

All is lined up properly as you describe.

I took a closer look at the impeller and it is not perfectly symmetrical - I don't think the plastic needle wheel part was properly affixed to the magnet - it's slightly off-centre.

When I get the new impeller - I'll report back.

 

[Clydester88]

I installed the new impeller (the original was definitely defective in comparing the two) but the skimmer will still not restart underwater.

I discovered that water is somehow entering the airtube when the pump is shut off - I believe it's coming in from the hydrofoamer.

I checked both air tubes for leaks (there are none) and ensured they were firmly attached at all points.

If I lift the skimmer out of the water and then resubmerge it, it restarts since water exits the air tube, and it stays running.

In the manual I noticed there is a bushing and attenuation disk mentioned - is it possible I'm missing these - it's not clear where they fit and I don't see them.

 

[rvitko]

The bushing and disk are under the 9012.700 drive unit, they are down in the pump at the base of the shaft.

Possibilities would be the top cover of the pump is on wrong or the pump is not clipped in the right position or the rectangular plate on the bottom of the pump is not in place.

The pump should be clipped into the intermediate plate needle wheel facing up. The cover with the air intake can twist on two ways, one way it is symmetrical and that would be correct, if it is asymmetrical so that the wider bar is off to one side, that is incorrect. On the bottom of the pump is a rectangular opening with a small plate that pressed into it that says Tunze, if this was missing their would be a loss of suction.

 

[Clydester88]

I assume you mean the 9012.047 drive unit?

The top cover of the pump is on correctly, the pump is clipped in the right position and the rectangular plate on the bottom of the pump is in place.

I'm receiving a new housing as one of the clips is broken (I had glued it temporarily but still had the issues described previously). When I receive it, I'll post pictures of my assembly to ensure it's as you describe.

 

[Clydester88]

Well, the new housing solved the streaming bubble problem - it must be a tighter fit.

The only remaining problem is that the skimmer won't restart unless I blow into the airline to clear it.

Here are my assembly pics...

 

[rvitko]

Everything looks correct, are you sure the airline is not pinched at any point?

 

[Clydester88]

Yes, definitely no kinks. It's skimming very well. It just won't restart without me clearing the air tube.

 

[rvitko]

Any chance you could email me a short video of this issue so I can get some feedback from Tunze Germany or Tunze France (our main engineers) I am at a loss.

Tunze at sbcglobal dot net

 

[Clydester88]

Done.

The first part of the video is normal operation. In the 2nd part, where the cup is removed, this is after restart. The needle wheel is spinning, but the skimmer isn't getting air. I blow in the tube and it starts normally. The valve is completely open in both cases.

 

[rvitko]

Try raising the skimmer approx 1cm or about 1/2", whenever bubbles are escaping the front and their is not a clear surface skimming effect (waterfall into the skimmer) the usual cause will be it is submerged too deep and that would also potentially affect the air intake.

 

[Clydester88]

I had to clip some of the plastic lip on the rim of the tank to raise the skimmer as you suggested. It eliminated the waterfall and is surface skimming better - I had a slight film on the surface before, but now it is gone.

Unfortunately, the skimmer still won't restart properly.

 

[rvitko]

OK, I will get back to you when I hear more from the engineers.

 

[rvitko]

What I have heard back is that you should get another impeller, it likely has a defect and that is the cause of the poor starting and they sounded quite certain of that.

 

[Clydester88]

As per post #6, I've already replaced the impeller - unless the replacement is defective as well.

A new motor block with a new impeller is on its way. I'll update once I receive and install it.

Thanks for your help.

 

[rvitko]

Yes, the consensus was the replacement would also be defective.

 

[Clydester88]

I finally received a replacement motor blocked and it solved the problem.