Cleaning used rock

[OutsideBrian]

I’ve tried muriatic acid and bleach on these rocks and cannot get rid of the black / brown dingy look.
Any suggestions, should I worry about it?

 

[Peace River]

I’ve tried muriatic acid and bleach on these rocks and cannot get rid of the black / brown dingy look.
Any suggestions, should I worry about it?

Please accept this as a genuine question and realize that I am not trying to be funny - is your goal to have attractive rocks or to kill all of the organic material? If you use enough muriatic acid that you create a lot of foaming then it is breaking down the organic matter (you may need to do it more than once), but it may or may not improve the look of your rock. Good luck!

 

[Mastiffsrule]

Hello, quick question. Sometimes man made rock will do that. Take a look closely at the rocks, see if you see anything weird, or does it just look like rock. Also what was the source of the rock.

 

[OutsideBrian]

I guess I just assumed it would turn white once it was “clean”
No idea of the source, it was free used rock that I picked up.

 

[Aquavaj]

If theyre not coming off with those then the rock was probably made naturally that way. It might look ugly initially but once coraline and corals cover them it won't matter anymore.