About that Red Encrusting Algae (not Cyanobacteria)...

[WheatToast]

Up until a little over a year ago, I always assumed all the hard, red encrusting algae we find in our marine tanks was just another variant of Coralline algae. Boy was I wrong! I eventually came across this site which made me realize that this "red Coralline" might actually be of the genus, Peyssonnelia. Yet as I dove further into this rabbit hole, I discovered other, similar red encrusting algae, such as Hildenbrandia.
This leads me to the question, how exactly can we tell these different varieties of red encrusting algae apart? Though they have similar care requirements, I would hate to misidentify these algae without knowing.

 

[taricha]

a couple of thoughts on wanting to distinguish these encrusting red algae from "coralline".
Coralline algae is not one genus but quite a few.
if you can't separate them by touch or scraping a fingernail, then a drop of acid ought to easily distinguish by visible bubbles a calcified algae from a fleshy one, I would guess.

 

[reddevilant]

I’m not sure how to tell the difference but I found a whole lot of Hildenbrandia-covered rocks while on a field trip for a marine biology class I’m taking this semester. But I stupidly didn’t grab a rock to take back to my tank

 

[TriggerFinger]

I have this “red coraline” all over my rocks…never knew it wasn’t coraline. Wow.

Edit; comparing to OP pics, I do not have any fleshy bits. Mine is all calcified and hard to scrape off. So maybe I do have a red coraline?

 

[WheatToast]

Edit; comparing to OP pics, I do not have any fleshy bits. Mine is all calcified and hard to scrape off. So maybe I do have a red coraline?

None of the algae in the picture was fleshy at all, similar to true Coralline. However, I am beginning to believe that all “red Coralline” is not true Coralline, despite their similarities.

 

[Udest]

I've had some in the past it seems to wax and wane , but perhaps another way to I'd what you have is to see if it will glow under the blue lights , I noticed some do and others don't.

 

[Enchelycore]

I have some of that growing on my glass. It’s seems very tough but doesn’t seem calcified. When I razor it off, it comes off in a tough sheet instead of crumbling like other coralline algae’s.

 

[eggplantparrot]

had something like this when i first started.

I picked up a piece of live rock from the LFS as it had this glowing hot red/orange patch. turns out that's the color when it starts to die off.

it took over my tank at one point, and would plate out from the rock.

it was leathery to the touch and a tiny bit slimey. it flexes quite a bit before breaking, but did feel brittle.

when soaked in acid, it fizzed so it is calcium based, but would leave the leathery red skin in the acid.

now it is no longer dominant in my tank but still shows up in patches that look exactly like the basic pink stuff, just red.

 

[Uzidaisies]

I have both I reckon, but on this zoa plate it looks like the red is dying off and underneath is purple. Ignore the Briopsis.

 

[Shon]

If you have any Caribbean live rock, you might have an encrusting bryozan.

 

[taricha]

but perhaps another way to I'd what you have is to see if it will glow under the blue lights

All red algae (including coralline), and red/brown cyano possess the red pigment phycoerythrin that glows red under a blue/uv light, but the below detail matters...

I picked up a piece of live rock from the LFS as it had this glowing hot red/orange patch. turns out that's the color when it starts to die off.

yep. Something happens to the pigment centers when the algae dies or is damaged. The red pigment fluoresces orange instead of pink.....

bottom left: two pebbles with coralline algae.
bottom right: under fluorescent blacklight (~365nm) they glow pink
top: after a drop of vinegar, the pebble on the right fluoresces brighter and orange.

I do not think this property is unique to coralline algae, I think any red algae that had its chloroplasts similarly damaged would shift fluorescence in this way.

 

[Udest]

Yeah I had spots that florced bright orange before they died off , also it had the plating habit another poster mentioned , as of now I haven't seen any more if it in my tank I believe it's likey very sensitive to peroxide.

 

[WheatToast]

Bump

 

[eggplantparrot]

I just found a pic of when the red stuff took over my tank! Not sure if it's the same stuff though.

You can clearly see orange spots where I guess it was dying.

 

[WheatToast]

I just found a pic of when the red stuff took over my tank! Not sure if it's the same stuff though.

You can clearly see orange spots where I guess it was dying.

You had the plating variety?! Wow! I have only seen that once in captivity!

 

[Supa]

You had the plating variety?! Wow! I have only seen that once in captivity!

So is it not a “good” algae?

 

[WheatToast]

So is it not a “good” algae?

On the contrary, it actually seems like a nice algae to have around for aesthetics, though I am not sure how fast @eggplantparrot ‘s plating variety can grow. The non-plating varieties seems to grow incredibly slowly.

 

[Zoa_Fanatic]

I've had some in the past it seems to wax and wane , but perhaps another way to I'd what you have is to see if it will glow under the blue lights , I noticed some do and others don't.

Mine glows in the blue lights. It’s all over my tank. It’s been slowly growing for over a year now.

 

[eggplantparrot]

It grew crazy fast in my tank when it was new, and would encrust first, it started playing I guess when it ran out of room. Super brittle and would break off and clog my hose when doing waterchanges.
I still have it in the same tank but much less and doesn't plate anymore

 

[sensaidavid]

Hildenbrandia rubra we need to get Cymbula sanguinans in the hobby. Any suggestions where to find?