Brown stuff on rocks?

[silicon_dt]

Heya!

I have some brown stuff growing on my white rocks, I have no clue what it is. I have tried Algae Destroyer and still does not get rid of it.

It only grows on stuff that the lights are shining on. Like under the shadow of objects in the tank it does not. I can do a water change, which I do pretty regular and it gets most of it off, but just wondering if anyone knew anyway to get rid of it.


Thanks for your time.


EDIT: I do not leave my lights on all the time, forgot to mention that.
I have an automatic light turn on/off. So its on from 9am-10pm.

 

[The-Wolf]

It's called diatrom and is found in new tanks
the best wat to remove it is by scrubbing the rocks
you could also get some apple snails and or otos (otocinclus affinis)
both will happily eat the diatrom.