help to identify this algae

[Conika]

Hello,

If someone can identify this "algae" brown ...
I have it on rocks and sand but the tank have only 9 months.
I think it is diatom but i am not be sure ...

Thanks

 

[AJsReef]

Kind of difficult to tell from the picture above, how does it look in your tank?

Any stringiness or bubbles?

 

[Conika]

no stringiness, a little bubble under the film but not everywhere and at the end of day. Under microscope, it is moving but very very slowly in the same direction. I have 0 nitrates with red sea test (algae control) and 0.03 ppm de PO4 with checker Hanna ULR. I stop NOPOX (only 0.5 for 200 l par day before). The tank has 9 months. I would like to improve NO3 but it is difficult. My RO water is ok for me.

 

[Conika]

An other view