What is this stuff??
 

This stuff invaded my tank about a year ago and refuses to leave. It is like a brown fuzz all over my rocks. I took out all my rocks and scrubbed them with a toothbrush but the stuff came right back in a day or two. If anybody knows what it is and how to get rid of it, please let me know.

Thanks

Sounds like cyano to me.

+1
Too many nutrient in your tank
feed less
Change water more frequently.
What are your water parameters?

I was out of the country for a month so haven't checked my water parameters. I tried to upload a picture of it but it wouldn't work for some reason. I just upgraded my protein skimmer, do you think this might help?

yes

I finally managed to get some pictures. Please have a look