Brown Gunk Growing In Conditioned Water Jug

[keithp]

I have a plastic water jug I use to store conditioned water to use when I do water changes. One jug I had for 2 years, and it has started growing thin patches of brown gunk on it, the water remains clear, but if you scrub the water jug brown slime comes off. My fish seems to be fine, I was wondering is this algae or bacteria, and is it beneficial?

 

[Curiosity101]

Algae more than likely, and no it's not beneficial but it shouldn't be harmful either. Do you keep the jug somewhere where it receives any daylight? Doesn't have to be alot, just some. If so is there a cupboard you could keep it in instead?

 

[keithp]

It's in a cellar but gets some artificial light.