Is this cyanobacteria and should I be concerned?

[Ralph Ritoch]

The red stuff was on the coral when I bought them and the brownish stuff was on the liverock but it seems to be spreading. This tank has only been cycling for 20 days but at 30C (86F). I have also noticed that the Specific Gravity seems to be lowering for the past 2 days so I've added more salt to bring it back to 1.022 (about 4 tablespoons of synthetic salt). The tank is nearly 40 gallon and has 2 clownfish, 2 starfish, and 2 coral.

 

[Mr Fishface]

Can you use a turkey baster to blow away the red stuff? If so that would by cyano. The brown stuff looks a bit more like diatoms to me, nothing to worry about just a normal phase that all my tanks have gone through anyways.

 

[Ralph Ritoch]

Can you use a turkey baster to blow away the red stuff? If so that would by cyano. The brown stuff looks a bit more like diatoms to me, nothing to worry about just a normal phase that all my tanks have gone through anyways.

The red stuff doesn't come off easily. I haven't tried to scrub it but none of it came off when I accidentally focused the wave maker directly at it. Could this actually be red algae?

 

[Mr Fishface]

The red stuff doesn't come off easily. I haven't tried to scrub it but none of it came off when I accidentally focused the wave maker directly at it. Could this actually be red algae?

If it doesn't blow off easy it's def not cyano then. It would be some type of red algae then, yes. I would let it grow a little and see. Most red algae is easily eaten by any type of herbivore unless it's coraline. I would only worry if it starts to smother your coral or seems to grow super fast. Keep an eye on it and let us know