White fungus on walls and substrate

[d_em]

This is been persistent for a few weeks. I suck up small chunks and it goes away for a few days then slowly creeps back. Today I got home from work and the filter was off (aquaclear, and power went off and back on) and it spread quite a bit, enough to worry me enough to make a post. Is this something I should remove the fish for because its dangerous? How do I treat it? So far the tank is healthy and since its presence I've only lost 1 Amano Shrimp, so I can't really say its bad, but I have no idea what it is.

Also, I've had this same thing in 2 of my other tanks as well, but it eventually went away with the method I described earlier. 

To give as much info as possible, 7 gal cube, injecting co2, on an hour before lights, off an hour before lights go off. 

Inhabitants include 2 amanos, 10 CPDs, and 3 young L397 plecos, lots of plants

ph-7.2

nitrates-15ppm

nitrites-0

ammonia-0

gh/kh-150ppm/50ppm

temp-75*

Edited November 10, 2021 by d_em

[Guppysnail]

Is this a newer setup. It is harmless biofilm/bacteria colonies if it is. You filter (I am oh so familiar with Aqua clear) being down allowed excess nutrients in the tank vs being consumed by the filter bacteria. It should eventually go away. I had 1 tank that it nagged about for almost a month before it started receding. I love your stones. I got one tiny piece a long time ago in a bargain jumble bin at my lfs…can’t for the life of me remember it’s name though. 

[eatyourpeas]

I agree with @Guppysnail that it looks like biofilm. Nothing to worry about. That looks like Seiryu stone, and it is beautiful!