What is this grey stuff on my sand and rock?

[ketokmagic]

Greetings,
What is this stuff on my sand and rock?

Tank has been up since January with live sand and rock.
First fish added in April. First corals added in June.
Went through a diatom bloom in June.

Currently I have a grey / black substance coating portions of my sandbed and much of my rock. Googling around most of the reports I read led me to believe it might be some variation of Cyano.

I have started having some of the red cyano appearing in my sump refugium. But this stuff in my display tank looks different. It blows easily off of the rocks in ‘flakes’ with a turkey baster. My rocks are also getting a decent amount of green algae on them as well. (But it isn’t hairy at all. It is very think and close to the rock.)

I’ve tried the 3 days of darkness routine which seemed to have no effect on the grey stuff in the display tank. (although I did see a reduction in the algae and slime in the refugium.)

Over the weekend I decided to pick up Chemiclean from my LFS and applied the treatment on Sunday. I know the instructions say to wait for 48 hours before doing a 20% water change and then administering a 2nd treatment, but the results I’ve seen folks share on youtube and in forums suggest a fairly dramatic impact within the first 24 hours. However I’m seeing little to no reduction of this grey/black stuff on my sandbed so far. The red slime in my refugium is completely gone now, which isn’t a surprise.

I’m curious as to opinions on what this grey stuff is?
thx!

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60 Gallon Display 48”x13”x24”
35 Gallon Sump
Bean Animal Overflow
Carbon / GFO reactor
Dosing Kalk via ATO
Refugium with Chaeto
Skimz Protein Skimmer
Current Orbit Marine LED lights
RODI water

Nitrate - 0
Phosphate - <.25
Calcium - 440
dHK - 10
Magnesium - 1000
1.025 salinity

 

[whosurcaddie]

It looks like cyano to me just a different color variation. What is your source water? How often do you feed and what is your water change regiment? Almost all algae outbreaks are due to excess nutrients. Look at how you run your tank now and figure out what is causing the excess nutrients and solve it.

.25 phos with algae present in the tank means you have a real po4 problem.

 

[ketokmagic]

Thank you - water is RODI. I've been doing 5 gallon water changes every week like clockwork.

 

[CStrickland]

I have a tiny bit of cyano on one frag plug in my tank, and I think flaky could describe it. It's like little bits of plastic wrap or cellophane kinda? I figure it's just mats of bacteria.
Have you tried playing around with your powerheads to get better flow on the sand? If old food and poop settle there the Cyanobacteria can lay those those mats right on them and eat away
Idk, maybe this kind doesn't mind chemiclean?

 

[ketokmagic]

Thanks CStrickland. I am experimenting with powerhead positioning. I have a Gyre 130 and an MP10 - for a tank this size it seems like I have plenty of flow. But I'm new enough to this that my perspective lacks experience...

This morning I am finally seeing some pullback on the grey. Late this afternoon will be the end of the 48 hour period - so it appears this is cyano as whosurcaddie said and the chemiclean will be the solution after all.