Tunze Nanostream concerns

[louist]

So, I took my Nanosteam 6025 apart today to clean out the algae growing inside, and guess what I saw? The shaft appears to be rusted :wall:

This pump came off the first shipment (Australia) and has been in operation for ~2 months (give or take a few days).

The photos are 100% crops from the original unaltered image. It was taken at life size magnification (1:1) with flash and no other modifications. The photos are focused at different part of the shaft to show their states.

The pump still runs smooth and quiet, however the rust does worry me.

This pump is run 24/7, but is shut off during feeding and water changes. During feeding time and waterchanges, the pump will often dry out because the water level in the display drops below its mounted position. I am not sure if this drying/wetting cycle promotes the formation of rust, but I doubt it sits above water long enough for the shaft to dry out. It has not been exposed to any corrosive chemicals such as acids or oxidising agents.

http://www.zengalleria.com/images/aquarium/CRW_3257.jpg
http://www.zengalleria.com/images/aquarium/CRW_3260.jpg
http://www.zengalleria.com/images/aquarium/CRW_3261.jpg

What are your thoughts?

[jameshongth]

Rusty...:confused: is the shaft make of steel?

[rvitko]

Did the shaft come out? The shaft is made of stainless steel and it does develop some superficial corrosion like any stainless steel material. It is not the same rust though that standard iron or steel experiences though because it does not result in pitting or rust through. The shaft looks physically damaged though, like it was scored or abraded and likely the pump needs to be replaced. It probably has the same issue we have seen in the states, a loose magentic rotor fit allows the magnet to oscillate as it spins and grind and damage the shaft.

[louist]

Roger,
Nope, the shaft is still in the pump.

I am concerned because the rusting does appear to have a pitting effect on the shaft as seen in some of the rusted patches.

Thanks for you fast reponce, I will speak to my local distributor to see what can be worked out regarding this. Perhaps they can send the damaged pump back to Tunze so the engineers can analyse it.

[rvitko]

It could be just the individual shaft but the ones I have seen here like that were not in the pump anymore and were badly adbraided. I am not a ametallurgist so I can't say if maybe the iron accumumlates more in areas during the manufacturing process. Normally, SS will get a brown surface discoloration but no major pitting or corrosion.