# Purple Algae in a Freshwater Tank?



## Rane

Hey guys, 

I've got this weird purple algae in my tank. So far it's not been causing much trouble, so I'm not too worried about it. Curious, more so. I've not been able to find any source that would give a likely ID on it. Purple seems to be a color almost none-existent in the freshwater algae world.

I read that it could be possible for freshwater cyanobacteria to be purple, but the sources I've read tell me that cyano should be slimy and smelly. This stuff is neither very slimy, nor can I detect any obvious stench. 



















Seems to only be growing right under the light on the driftwood. Any ideas what it might be?


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## steven p

Not a clue what it is.. but its definately intersting.


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## TexasCichlid

Never seen that one before.


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## Complexity

I've never seen it before either, but there is a freshwater red algae. It's part of the Rhodophyta family which I believe is the same as BBA. It crosses over between saltwater and freshwater. Usually, only the black version is seen, but I've read that there is a red version as well.

I'm not certain that's what this is, but it's the best guess I can offer at this point.

I'd squirt some H2O2 on it and see if it reacts. If it does, then that may be the way to kill it. Of course, then the question is whether it will return, and if so, what's causing it. But for now, let's at least see if it will react to H2O2.

BTW, where did you obtain that driftwood? If that's the only place where this stuff is growing, it might be best to take it out and boil it. I'm wondering if it's contaminated with something that's causing this stuff to grow.


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## Rane

Complexity said:


> I've never seen it before either, but there is a freshwater red algae. It's part of the Rhodophyta family which I believe is the same as BBA. It crosses over between saltwater and freshwater. Usually, only the black version is seen, but I've read that there is a red version as well.


Interesting you should mention a black version. I have another algae that grows in all my tanks. It has a similar, slightly rough, texture and grows in a similar manner as well, yet is in fact black. I usually only see the black algae on my rocks (I haven't had driftwood in a tank before). Kinda' going out on a limb here, but is there any way the driftwood could affect the color of the algae? 



Complexity said:


> BTW, where did you obtain that driftwood? If that's the only place where this stuff is growing, it might be best to take it out and boil it. I'm wondering if it's contaminated with something that's causing this stuff to grow.


I collected it locally here in the Mojave Desert. Unfortunately, it's far too large to boil. I'm actually not too concerned about the algae spreading. So far it's been growing quite slowly and is only growing in that one small area. I was mostly just curious as to what it might be because of its strange color.


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## Complexity

I can't find anything that even remotely appears to be the same thing. I don't think it's Rhodophyta based on its appearance. BBA is fuzzy (hence it's name, "Black Beard Algae"), and this stuff doesn't look like a red version of BBA.

In fact, I'm not even sure it's an algae. It may be a mold, fungus, or bacteria. I honestly don't know.

My best suggestion would be for you to look on the internet for university professors that deal with freshwater algae, mold, fungi, and/or bacteria. Send them an email with those pictures and ask for help. I've done this before and have found many university professors very happy to respond. Be sure to tell them where you found the wood as the location may be key to the identification.

If you do get an identification, I would greatly appreciate it if you would post it in this thread. I'd very much like to know what it is. Even if you can't get an exact ID on it, it would be nice to get a general idea of _what_ it is.


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## FlyingHellFish

Me too, it laughs at Excel and asks "What is that? It tickles!"

From what I gather, it's what Complexity said, a form of Rhodophyta which is hard to kill. If you are able to easily get rid of it, then it's probably not the same type of algae I deal with. You can try a solution of Hydrogen Peroxide 3% and gentle scrub it with a toothbrush. 

It will come back though, I have no idea how to stop this either.


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## Rane

Thanks for the suggestion, Complexity. I emailed a professor at Berkeley who seemed qualified. Hopefully she'll respond. 

@FlyingHellFish What does the algae feel like when you touch it? The stuff I've got is almost rough feeling.


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## Complexity

FlyingHellFish said:


> Me too, it laughs at Excel and asks "What is that? It tickles!"


Very odd because Rhodophyta (at least the black BBA version we normally see) is killed by Excel. So the fact that Excel doesn't affect it actually makes me believe even more that it's not Rhodophyta. However, I can't be sure since I don't know if the red variety of Rhodophyta responds the same as the black variety.



Rane said:


> Thanks for the suggestion, Complexity. I emailed a professor at Berkeley who seemed qualified. Hopefully she'll respond.


Excellent. It's a tough time of year with the fall semester starting up, but let's hope she takes a minute to get back with you. If not, email other professors. You'll eventually get a response from one of them. I can't wait to find out what it is.


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## FlyingHellFish

Excel does work, but it gets expensive as you must use a ton on it. I just found Peroxide a lot better at killing it.


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## Calmia22

If I had that in my tank and it didn't harm the fish or plants I would keep it! Lol It's pretty!


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## Jaybee Goh

*Me Too*

I got it too.. 
You got the reply from the expert?
I interested to know what is it as well..


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## geisterwald

Calmia22 said:


> If I had that in my tank and it didn't harm the fish or plants I would keep it! Lol It's pretty!


Me too!


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## Darkblade48

The original post was from 4 years ago, so you may not really get an answer.

However, based on what I can see, I would say that the algae is BBA, but it is dying (it often turns pink/purple when dying).


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