Green Inside CW5000 Chiller Silcon Tubes - Help Please

[Doug Fisher]

I recently looked at my semi-transparent silicon tubing that runs from my S&A CW5000 chiller to my glass tube CO2 laser. To my surprise, both the inlet and outlet tubes had a rather brilliant blue-green color cast to them. The color didn’t seem correct to be algae growth but I wondered if I maybe had an algae variety I had never seen before now. Therefore, I proceeded with a plan to put a cup of bleach in the water reservoir, let it circulate through the system for an hour or two and then do multiple complete changes of the water to remove any remaining algae and bleach out of the system.

The bleach solution was not effective to remove the blue-green from inside the tubing. My next step was to disconnect the tubing running between the chiller and the laser in order to look inside the tubing. As you can see from the pictures this does not appear to be algae. It is a strange coating. To me, it looks similar to copper corrosion. It removes easily if you run a bottle brush or similar down the tubing.

Has anyone experienced something similar? If so, what was it and how did you stop it? I have never used anything but fresh distilled water in my system from the first day I have owned it. This is the first time I have experienced this. I am wondering if it is copper corrosion residue coming from something internal to my CW5000 chiller. I don’t think anything else in the laser cooling system has copper in it.

Thanks!

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[Kev Williams]

To find out if it's copper, do you have any liquid metal oxides handy, such as Aloxide or any of the various types/brands of oxides designed to blacken anodized aluminum or lacquered brass after engraving? Or gun barrels? ANY of those will turn copper black near instantly. Personally I don't think it's copper at all. I'm wondering if the chiller factory tests them with and additive, such as the stuff you put in waterbeds to keep guck from growing, or something to keep the smell down? I remember in our waterbed days that stuff we added was blue... ;)

[Doug Fisher]

Unfortunately, I do not have any of those.

I have had this running for about two years so it is kind of strange for this stuff to start showing up now. I have email S&A / Teyu customer support and will report back if they have any interesting thoughts.

Thanks.

[John Lifer]

Birchwood Casey is a brand of those oxides.
Here is picture of two I have415557

Some Walmarts may have the Brass, Online either Walmart or Amazon carries them for about $8 to $10.
Might be worth it to get some to check.
My System still has the original tap water from when I installed the machines in Dec 2016.
No staining at all. No algae, clean as when I put it in the chiller (and we have relatively hard water here)

Now ONE thing I have seen is an oxidizing of the silicone inside the laser. White powder all inside the housing. I clean about every 6-12 months.
But nothing inside the tubing.
So far the tubing is still in good shape, Just checked, and actually not any perceptible dust now, it's been about 2 months since cleaning.

[Doug Fisher]

Thanks for the replies.

From what I have been able to find in the overclocker (water cooled PC CPUs) and aquarium forums, some tubing does this as it ages. Speculation revolves around leeching of plasticizers but there isn't a definitive answer. There are a couple of short sections of what appear to be PVC tubing in the cooling loop on my laser and that does not show this. My guess is that my machine came with some cheap tubing and/or a batch of poorly made tubing. I am not sure what I will do at this point. I can replace it but that involves pulling the tubing off of the glass tube's end fittings. It might take some serious effort and these end fittings are a known failure point where they are attached by epoxy or whatever. I am not sure it is worth the chance of killing the tube.

[Doug Fisher]

FWIW, the reply from S&A Teyu:

"Please note that our chiller don't have anything like the color,and the coil inside the water tank is made of stainess steel,please check whether is caused by the laser."