is this diatom or cyno

[boxfish]

those redish ones

[boxfish]

...

[dradttg]

I think it is cyno.

Diatom is light brownish. For my it only grows on my glass.

[giantbicycle]

saw some bubbles together with it...IMO , its Cynao..

[jesperlam]

Have those in my main tank before. Those algaes lies on the sandbed thats has low flow. After i increases flow on that area, the algae are not seen anymore...

[Gouldian]

Have those in my main tank before. Those algaes lies on the sandbed thats has low flow. After i increases flow on that area, the algae are not seen anymore...

Its Cyno.

Since it is in the sump, I believe the water flow might be insufficient thus you might want to place a powerhead to move the water a bit.

[boxfish]

Noted.

Thanks everybody!