Is this Cyano or Coralline?

Eel Steve · Aug 12, 2015

Big debate about it in my facebook groups, I thought I'd try to get the general consensus of a forum full of experts!

Below is a picture of a rock in my tank (duh.)

The purple circle at the top of it is a coralline encrusted frag plug from my LFS.

Are the pink spots on the rock the good stuff, or the bad stuff?

twilliard · Aug 12, 2015

Its coraline

ReefMadScientist · Aug 12, 2015

Its not coralline. Its the beginning of a bacteria bloom on your rocks which is part of the initial cycle process. Coralline comes after you cycle your tank and rocks.

ReefMadScientist · Aug 12, 2015

welp 50-50% so far LOL

iReef86 · Aug 12, 2015

Looks like old coralline that did not lose its color. I have some on my dry rock that I started my 250g DD with.

BryanS4 · Aug 12, 2015

I can't see it very well, but IMO it would be cyano. The rock looks really new and coralline is going to start growing on the glass and plastic surfaces long before the rocks.

ReefMadScientist · Aug 12, 2015

Add a poll!!!

twilliard · Aug 12, 2015

No way! The true test would be if it can be blown off with a baster

I doubt cyano.. well not yet

Eel Steve · Aug 12, 2015

I cant get it off with a baster, and it doesn't even scrub off with a bristled brush easily (or at all really)

Eel Steve · Aug 12, 2015

ReefMadScientist said:
Add a poll!!!

(How do I add a poll to this thread?)

ReefMadScientist · Aug 12, 2015

It may be too late. On your original post, click on thread settings or something like that...

BryanS4 · Aug 12, 2015

Yeah if you cant blow it off its not cyano. Probably old coralline like someone mentioned earlier.

Eel Steve · Aug 12, 2015

I dont remember them being on the rocks before is all. Also, does old coralline have a higher chance of spawning new stuff or no?

ReefMadScientist · Aug 12, 2015

Can you blow it off with a baster?

As for your question no - not if it was dead. New coralline will just grow over the old areas.

twilliard · Aug 12, 2015

Eel Steve said:
I cant get it off with a baster, and it doesn't even scrub off with a bristled brush easily (or at all really)

Yup coraline it is!
Just watch it grow everywhere and then do the annoying task of scraping it off the glass one day

Oceansize · Aug 12, 2015

My guess is coralline. It appears to be the same color as the coralline on the plug, and it's not growing out the way cyano does. Plus, it's purple. I have found that dead rock can produce coralline pretty fast if the dead rock used to have coralline on it before. Cyano spreads very fast, coralline does not.