Black sand?

[Schulks]

I haven't ran into or seen this and I've been keeping this aquarium for over 2 years now. My sand is turning kind of black (on top) in my lower flow areas. I recently found motivation and have been taking better care of my aquarium. I only have a few softy frags and even they've been having a hard time so..

I've done a few extra water changes the last couple weeks, more water tests, scrubbing the glass, got a bunch of new inverts, got a new powerhead, tossed in some carbon, and replaced my old return nozzle with a nice RFG nozzle. It has been lookin spiffy

From the little I read I think it is low O2. I might need more surface disruption. I thought I knew what good surface disruption was after so long. See the youtube link for video of surface but I don't think you can really see a video well for that. I adjusted the nozzle to see if it clears up but I'm not sure how long that could take.

Nitrate: 26
Phosphate: 0
salinity 1.025
PH: 8.2



Video is before adjusting my nozzle

The camera kind of makes this look red but it is much much more black.

 

[Rjukan]

It looks like cyanobacteria to me. Tank looks great though! Nice work turning it around, that's something I've been doing since the beginning of Dec too haha.
I'll bet it clears up on its own with your increased husbandry.

 

[ReeferHD]

most likely cyano, with lower nitrates it should go away

 

[Reefer Matt]

Do you vacuum the sand?

 

[Schulks]

Do you vacuum the sand?

Yes, normally my sand is very pristine looking. I can vacuum around the rocks really easy.



Im not nearly this smart but I had a different issue with my mixing station awhile ago.
If O2 is low does that also lower the PH? I think that's true so that might contradict my theory.

 

[Schulks]

Ok so the black started going away after I made this post. Then I went to bed/work the next morning. When I came home that night the black had increased noticeably. So I thought it is because I shut the door to this room whenever I am not in it. My house has a really old HVAC system.

I left the window open all day yesterday and the black is almost completely gone. I am pretty sure this room just gets really stagnant really easy.