ID on some tube looking algae

[DDenny]

Not sure what this is had to add a flashlight get a decent picture. I know I have some GHA in the back part of my AIO tank but the tube looking algae has me stumped

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[vetteguy53081]

Looks more like sponge. What type of water are you using and is tank at or near a window?

 

[DDenny]

Water RODI with Red Sea Blue. That is in the back middle chamber of my AIO. Not near a window and the closest window usually has the curtains drawn with a little gap for natural light in the house.

 

[vetteguy53081]

Water RODI with Red Sea Blue. That is in the back middle chamber of my AIO. Not near a window and the closest window usually has the curtains drawn with a little gap for natural light in the house.

Dark area(sump) makes sense