# Black mold?



## etanico (Apr 2, 2010)

Hey everyone. I just came back from a weeklong vacation to find that my 5 gallon tank has been slightly overtaken by some black mold. It's in addition to the generic green algae that I'm going to work on in the water change I'm about to do. But what should I do about the black mold that has completely covered one of my large decorations? Is this something that could be fixed by a carbon filter media change? I haven't ever changed it, and I'm wondering if that's even necessary.

Thanks!


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## GwenInNM (Feb 2, 2011)

etanico said:


> Hey everyone. I just came back from a weeklong vacation to find that my 5 gallon tank has been slightly overtaken by some black mold. It's in addition to the generic green algae that I'm going to work on in the water change I'm about to do. But what should I do about the black mold that has completely covered one of my large decorations? Is this something that could be fixed by a carbon filter media change? I haven't ever changed it, and I'm wondering if that's even necessary.
> 
> Thanks!



I doubt replacing the carbon will take care of that. You should look at how long your lights are on, perhaps cut that back by a couple/few hours. I have no idea what the "black" stuff would be. Some type of algae? You could take the decoration out and scrub it clean without chemicals. 

Gwen


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## Byron (Mar 7, 2009)

It might be a type of cyanobacteria, which can occur as green to very dark black-green, and even red. As Amanda said, clean the decor, if it easily comes off as a slimy film it is probably cyano. A thorough water change will also help, but be careful. Depending upon your pH of the tank water and the tap water, a large water change could create ammonia poisoning. Take it slow.


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## CamryDS (Oct 5, 2009)

Byron said:


> It might be a type of cyanobacteria, which can occur as green to very dark black-green, and even red. As Amanda said, clean the decor, if it easily comes off as a slimy film it is probably cyano. A thorough water change will also help, but be careful. Depending upon your pH of the tank water and the tap water, a large water change could create ammonia poisoning. Take it slow.


I didn't think cyanobacteria can grow in freshwater, I've seen it grow rampant in saltwater though, but never heard of in fresh- good tip!


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## Byron (Mar 7, 2009)

CamryDS said:


> I didn't think cyanobacteria can grow in freshwater, I've seen it grow rampant in saltwater though, but never heard of in fresh- good tip!


Some of us have been plagued with cyanobacteria periodically. It is caused by organics, so fortunately it usually is connected to a high organic load or poor maintenance (infrequent water changes, overcrowding fish, etc). But it can also occur in this or that tank. I have had it a couple of times in bad bouts, but aside from that I sometimes see a tiny bit on floating plants. But it is interesting how it occurs in some tanks and never in others. It is usually considered in with "algae" problems, although it is a bacteria and not an algae.


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