white rocks turning brown?
 

i have scattered white rocks in my 10G and they are turning brown/becoming dirty.

is this some form of algae or just a natural occurrence?

It could be diatoms. Take one out and see if it comes off really easy. If it does it is diatoms.

so what can i do to combat this?

If the tank is less than 9 moths old just give it time and it will go away. If the rocks are less than 9 months old same thing. If it is an older tank then it may be an issue of circulation. It could also be a silica ornament that you have added to the tank recently that the diatoms feed off. I added a painted and fired ceramic ornament and for the first 4 weeks it grew massive amounts of diatoms because of the glass finish.

cool. the tank is relatively new... had it up and running since november. hopefully it goes away fairly soon lol

i do have a ceramic and fired decor in it. and it is a little heavier on that

Give it some time and make sure that you have some circulation around it. If there are any dead spots they will get it a little worse. My BN plecos ate it and I think otos will eat it so it might be a good thing in the short run.

otos love it, i see a dot of diatoms one day, the next its gone, with only one .5 inch oto in the tank.

well maybe after i move next week ill get an oto or pleco for it.. thanks guys

I read somewhere that if your rocks turn brown, it could be a lack of oxygen in the water.