mold or mildew in aluminum tank ?

[bigdave195412]

I purchased an aluminum 40 and was changing the valve to a din. I noticed the tank didn't smell right. I put an inspection light in the tank and noticed quite a few areas of black on the shiny aluminum sides. Does this sound like mold ? The smell is the main reason I suspect it. If it is mold, what is the safest and best way to remove it from the tank ?

 

[DA Aquamaster]

The black areas are "normal" and are the result of moisture causing some minor corrosion. Often you will see it in streaks where a water droplets ran down the inside of the tank.

In my O2 tech/cleaning glass it was discussed and was not considered a major issue in light to moderate amounts.

Tumbling is an option to remove it and being a bit on the picky side, I tend to tumble when it gets to be anything beyond a streak or two.

 

[oxyhacker]

It may very likely be just water discoloration, but bad odors from a tank should never be ignored, since they can warn of more serious problems. If it was my tank, I'd probably give it a good cleaning with warm water, detergent, and a whip, and then see how it looked/smelled.

The black areas are "normal" and are the result of moisture causing some minor corrosion. Often you will see it in streaks where a water droplets ran down the inside of the tank.

In my O2 tech/cleaning glass it was discussed and was not considered a major issue in light to moderate amounts.

Tumbling is an option to remove it and being a bit on the picky side, I tend to tumble when it gets to be anything beyond a streak or two.

 

[bigdave195412]

Thanks, I'll try that first and then go from there. In 30 years of diving i've never run across a cylinder that smelled like that when the valve was removed.