Hard copper colored deposit on glass ????

[rjk8619]

For the past year I have been developing a hard ( cannot be scratched off with finger nail) deposit on the glass along the gravel line. (see picts). I have researched this online and cannot find a answerer to what it is. Any help would be appreciated. All fish and plants are doing well with no problems.

It's a 50 gal. tank with under gravel filters with power heads and a canister filter outside the tank.

Thanks

 

[rjk8619]

Come on someone must have some experience with this. I 'm pretty sure its a mineral deposit but from what ?

 

[Brookster123]

Its algae, try shutting down filter for a bit and squirting h202 in the area. Let it bubble for 16 minutes and do a pwc.

 

[fishwonder]

Try a razor blade scrapper...

https://www.amazon.com/Stainless-Sc...ium+razor+blade+scraper&qid=1603193065&sr=8-2