Brown Bacteria? (with pictures)

[shawnriv]

Hi All,
I just installed T5 lights to my 48 gallon aquarium and this brown bacteria seems to be growing. To be honest, I'm not even sure if it's bacteria. It has grown all over the live sand and a small amount has grown on the top of my dry rock. I do not know what to do to fix this problem.
Thank you in advance.

 

[bang guy]

To me it looks like a type of algae called Diatoms. These are very common for hobbyists that are using tap water instead of purified water. It's not harmful, just unsightly. Most of the snails available in the hobby will eat diatoms so it's a good source of food for them.