Algae or Cyanobacteria? (With Photos)

[jpbp]

I have been witnessing a strange phenomenum over the white sand:

When lights are on the white gravel become brown...

after shut down the lights the sand become normal...white...

Anyone knows what it could be?

Is it bad?

Some kind of algae?... cyanobacteria?.. some other thing?

It happened since i introduced 1 kg of live rock...



with pigmentation:

...some minutes after switch the lights off, turn on again and ... :

not a vestige of the brown pigment...




Thanks

 

[seaham358]

Looks like diatom algae.... its a normal part of a new tank. how old is the tank.
Cyno is red and is slimy looking, can be green also.

 

[electrikat]

I've never seen diatoms react to light before. Mine usually just stayed brown all the time. The first pic definately looks like diatoms I've just never seen it disappear before.

 

[malkore]

I'd say diatoms, not cyano.

 

[klam]

I had some algae that reacted like that to the light and it turned out to have similar qualities to cyano.

 

[Nate C]

Diatoms...

When my tank was new mine went away after dark also...

In time they will burn themselves out - not to worry.

 

[seaham358]

How old is the tank?????????????????

 

[jpbp]

One year old...

 

[wlam18]

I have the same and tank is 4 mons old.....

 

[seaham358]

thats odd getting diatom in a old tank. Add any new sand? What type of water do you use.
If it gets slimy looking and blows off the sand easy then its cyno... 4 month old tank the diatom is normal.... 1 year IMO is not that normal, but I'm sure its possible.

 

[jpbp]

I am using tap water with calcium hidroxid