What is this growing on my LR?

[droog]

Looking like small patches of black. Is this Cyano bacteria or something else? I'm not sure how to tell between diatoms and cyano to other pests.

Tank is relatively new, setup in Feb this year. Parameters are pretty stable:

Temp: 25-26C
Salinity: 35 ppt (1.0264)
Ca: 450-480
Mg: 1300
Alk: 8.9 dKH

NO3: 0
PO4: ~0.03

I've been carbon dosing (using NOPOX) from day 1.

My rocks seem to have pretty good purple corraline growth for 6 months or so in the tank. Colony polyps are spreading (the ones you see there showed up spontaneously) and generally all my corals and fish seem happy.

The black "mats" of stuff have been growing recently (but slowly). Its on the rock work only, I did get some on the sand, but I have sand sifting stars that seem to be keeping the sand clean.

I also have 2-3 Aptasia on the other side of the tank nr the bottom. They have grown very slowly, so I'm just keeping an eye on them but otherwise doing nothing.

Filrtation is: carbon dosing (by dosing pump), skimmer. I also run dual reactors with a little each of GFO (phosban) and GAC (rowa carbon).

I've done 2 "3-days" light out treatment in the last three months - I didn't notice any big effects after doing that.

You can see in the picture that the snails are covered in coralne... one (picture 2) is now covered in black, much like the tops of surrounding rock

Any ideas of treatment plan (if any) I should follow.

-droog

 

[Sugar Magnolia]

Yes, looks like cyano. Syphon it off as often as you can. Are you using rodi water?

 

[droog]

Yep, I'm using RODI water and my TDS meter reads 0. I have been feeding a little more, as the number of fishes has grown.

I'll do a second round of 3-days lights out while skimming wet, and reduce feeding for a bit.

-droog

 

[droog]

Hmm. The black stuff does not come off the rock if I scrub with a toothbrush... could that still be cyano or more likely something else?

-d

 

[johnike]

If it's that hard, it just may be darker coraline.
Does it scrape off with a fingernail?

Nice looking tank, by the way.

 

[shesacharmer]

My first thought was black sponge which doesn't come off too easily. If it's really hard then Coralline.

 

[droog]

I will try another good scrub. If this is black coralline is that a bad thing or not?

Would a 3 days light out help or is that just a waste of time?

-droog

 

[65Stang]

Any update, Droog? Curious as to your experience, I have the same stuff I believe.

 

[droog]

Any update, Droog? Curious as to your experience, I have the same stuff I believe.

Hi, just saw this post, I was not subscribed for updates.

I believe this is Lobophora Variegata, of which there are three kinds. One forms ribbons, another sheets on rock and a third "encrusting" variety. The picture above seems to be the encrusting variety.

I'm running a small amount of GFO in a reactor along with carbon dosing (NOPOX) for Nitrate and PO4 management. This seems to be keeping the algae in check but not causing it to die off. (Maybe a little in places).

I'll give it another month and then try a Naso tang. Blonde Naso tang seems to be the most effective cure, some have success will sally lightfoot crabs. HTH

-droog