is this algae? need help

[snd637]

i dont know if its algae or what...
but im starting to see this lime green "stuff" spreading all over my rocks...what is this? is this algae? is this something that i need to take care of? is it dangerous to my corals or fishes?

thanks for ur help...

[Cutiewitbooty]

sounds like algae, do you have a picture? Are you using Ro/Di water or tap? Tell us about your tank, how big, livestock? What are your nitrates at?

[ycrazyy]

Sounds like an algae bloom. Is this a new tank that you are cycling? I have the same thing on my rocks right now, started when I began to light the tank more. It bloomed up and is slowly going away as of this week (can see the difference everyday). I had used RO/DI water as well to fill my tank and have done multiple water changes.