not sure what this is......please help

[nitro069]

I have recently this brown furry crap growing on my rock in low light areas mainly. it started about a week or so ago and is spreading throughout the tank. My nitrates are at 0 per api kit and test strip(best i can tell don't have a good test kit for that). no test kit for phosphates. My new skimmer i just bought i couldnt seen to get dialed in and it was only skimming about 1 cup of wet skimmate every 5-6 days. changed that out today and going to see how that works. any ideas on what this stuff is and if my skimmer could be the problem.

the first on is what is on my mp40. looks the same as what is on the rocks

Second one is of the rock

 

[yveterinarian]

I'm not sure what it is either but I wanted to ask how old your tank was.  Maybe it is one of the nuisance algaes that show up in new systems, like diatoms do.

 

[nitro069]

I'm not sure what it is either but I wanted to ask how old your tank was.  Maybe it is one of the nuisance algaes that show up in new systems, like diatoms do.

Tanks pushing 2 years. most recent diatom bloom was in October when i switched tanks and stirred some stuff up. lights out for three days a few water changes and ran gfo. cleared right up.

This stuff almost looks like heavy detritus  build up that will not blow off with a turkey baster.