Fuzzy stuff on the underside of rocks

[SandJ]

It looks like what is referred to as mulm. Here is a neat write up on it by @Paul B

"Mulm" in a Reef tank

I think one of the most important, and least understood or mentioned things in a reef tank is "mulm". That stuff that grows in the dark portions of a tank if it is set up long enough. "Mulm" is a combination of algae, sponges, bacteria, pods, worms, detritus, poop and any thing else that can...

www.reef2reef.com

 

[vetteguy53081]

Combination of algae and diatoms and agree on added CUC ( nerite, astrea and trochus)

 

[Brandon McHenry]

It looks like what is referred to as mulm. Here is a neat write up on it by @Paul B

"Mulm" in a Reef tank

I think one of the most important, and least understood or mentioned things in a reef tank is "mulm". That stuff that grows in the dark portions of a tank if it is set up long enough. "Mulm" is a combination of algae, sponges, bacteria, pods, worms, detritus, poop and any thing else that can...

www.reef2reef.com

Interesting read. It does look similar to the mulm but this tank hasn’t even hit the 1 year mark yet and it seems like that is more of a mature tank feature. Another thing is that while it does grow under and on the edge of rocks, it is still partially lit. It seems like the mulm is more of a complete darkness/cryptic thing.

Combination of algae and diatoms and agree on added CUC ( nerite, astrea and trochus)

I may have to get some nerites as well (I currently have the other two).

 

[Brandon McHenry]

Well I finally made it over to the micro lab at work and put this stuff under the scope. It seems to be a mix of green filamentous algae, diatoms, cyanobacteria and all sorts of other assorted life. Here are the pictures to see if anybody can ID any of the organisms present and how I may be able to remove these ugly accumulations

 

[Bret Brinkmann]

So basically it's mulm. Looks like mostly green hair algae, cyano, and detritus mostly. Some diatoms and even a baby bristle worm. What is the flow rate like under those rocks? I know you mentioned 2 MP40s at 50% which is great for the bulk of the tank, but I am thinking you have some dead spots in your rockwork. That would explain the buildup of detritus which could generate a local high nutrient spot as well, thus the higher growth rate there. Can you post a full tank shot and let us know where this stuff accumulates? Knowing what it mostly is comprised of you can treat for each component.

 

[Brandon McHenry]

So basically it's mulm. Looks like mostly green hair algae, cyano, and detritus mostly. Some diatoms and even a baby bristle worm. What is the flow rate like under those rocks? I know you mentioned 2 MP40s at 50% which is great for the bulk of the tank, but I am thinking you have some dead spots in your rockwork. That would explain the buildup of detritus which could generate a local high nutrient spot as well, thus the higher growth rate there. Can you post a full tank shot and let us know where this stuff accumulates? Knowing what it mostly is comprised of you can treat for each component.

This is a FTS. I’m currently dealing with a little bit of cyano as well. The stuff accumulates in pretty much all of the underhangs as well as the rocks along the back wall of the tank. It sways pretty aggressively in the current in all of those locations. The circles are a conservative illustration of where this stuff is.

 

[Bret Brinkmann]

Thanks for the picture and nice looking tank. Detritus settles in the lower flowing areas of the tank. While you definitely have good overall circulation, it looks like most of it is up high and at the tank, then drops off sharply in the caves. I suggest trying to get more flow along the back of the tank behind the rocks. I think that will help prevent the detritus buildup.

With the detritus gone, perhaps there won't be more nutrients concentrated in the simi enclosed spaces siding algae growth. Or maybe it will still grow but because detritus isn't on it that will make it palatable to the herbivores. I know you mentioned it sways back and forth but swaying current isn't the same as through current.

You could also try moving your rockwork around to get better flow through them but I'd hate to upset your nice looking corals.

 

[Gablami]

@Brandon McHenry so did it ever go away? I have some of that in my tank now too. I've just been blowing it off and waiting.

 

[Brandon McHenry]

@Brandon McHenry so did it ever go away? I have some of that in my tank now too. I've just been blowing it off and waiting.

Yes it did. I don’t really remember when but it was suddenly not there anymore. I didn’t do anything in particular to get rid of it. I think it probably has to do with the tank finding a more mature biological balance.

 

[Reefrats]

I’m dealing with the exact same thing. Odd that there is no clear ID for it. I’ve been blowing it off, brushing it off 1-2 times a week, doing weekly water changes, running a polishing filter, and it’s driving me nuts. I even tried UV with no luck. It’s under my rocks and on vertical surfaces of my rocks.

 

[vetteguy53081]

I’m dealing with the exact same thing. Odd that there is no clear ID for it. I’ve been blowing it off, brushing it off 1-2 times a week, doing weekly water changes, running a polishing filter, and it’s driving me nuts. I even tried UV with no luck. It’s under my rocks and on vertical surfaces of my rocks.

Any pics under white lighting?

 

[Reefrats]

 

[Reefrats]

for some reason I cannot upload images - see attached pdf with 2 images under 150 x magnification with an old USB microscope.

 

[vetteguy53081]

Can you do still images?

 

[Reefrats]

It keeps saying oops we ran into problems from the computer and iPhone. I will keep trying. I may need to take photos with a real camera and upload.

 

[Reefrats]

It keeps saying oops we ran into problems from the computer and iPhone. I will keep trying. I may need to take photos with a real camera and upload.

 

[Reefrats]

 

[vetteguy53081]

Thank yopu for clear photos. Looks like it Lyngbya. Lyngbya is often reddish or brown and is not, but rather a type of cyanobacteria. Even though it looks just like hair algae and is filamentous rather than slimy, it dislodges easily from the rock and good news is that it has no root or mat structure yet grows fast. Lyngbya species seem to grow very fast in warmer tanks, and spread quickly under low light. Aggressive manual removal will be necessary with use of a firm toothbrush or auto detail brush.
After cleaning (preferably in a bucket with some tank water, certain cleaners will help prevent future growth such as Chiton snails, cerith snails, nerite snails and small blue legged caribbean hermits.

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[Reefrats]

Thank yopu for clear photos. Looks like it Lyngbya. Lyngbya is often reddish or brown and is not, but rather a type of cyanobacteria. Even though it looks just like hair algae and is filamentous rather than slimy, it dislodges easily from the rock and good news is that it has no root or mat structure yet grows fast. Lyngbya species seem to grow very fast in warmer tanks, and spread quickly under low light. Aggressive manual removal will be necessary with use of a firm toothbrush or auto detail brush.
After cleaning (preferably in a bucket with some tank water, certain cleaners will help prevent future growth such as Chiton snails, cerith snails, nerite snails and small blue legged caribbean hermits.

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Oh wow I know lyngbya from monitoring reefs offshore but I guess it looks much different in a tank. I’ve been brushing with a soft bottle brush, siphoning out, scooping out with a brine shrimp net, and running a polishing filter and after my floss cup a klir filter roller. I have a refugium and my nutrients test 0 but I have GHA too that I pluck with hemostats. I’m doing a dr. Tim’s treatment now and I guess I need even more CUC. I have a large CUC but not the numbers Reef cleaners recommends. This sucks. It keeps coming back within a day of brushing/blowing it off. I will research lyngbya species. I have my red green and whites off and feed a tiny bit twice a day.