Algae ID and help!

[newfound77951]

Anyone know what kind of brownish/blackish algae this is and what might be causing it? It's in both my 55 and 36, and grows mostly on the stem plants and crypts, not on the swords. Neither tank is new so I don't think it's diatoms.

 

[jsoong]

Looks like what I have .... It is stuck to the leaves & can't be easily removed, grows in sheets, feels slimy & smells gross.

I believe that it is Blue Green Algae. From what I read, BGA can also be red, brown or even black, depending on species. The red ones are also called Red slime algae.

I don't have a cure for it ..... I am battling it to a draw by:
1. physical removal - pruning off older leaves.
2. adding KNO3 - since it is said that low N-P ratio encourages it
3. Increasing flow - BGA is sensitive to O2, my tank should be well aerated with a wet dry.

I've tried Excel & H2O2 ... not great results as my vals/hornworts are rather sensitive to this & I can't use too much. I ahve not try a total tank blackout, since experimenting with it in my QT shows that it takes 7-10 days to kill the stuff with blackout & I am not sure how my tank will do with such a long blackout...

Non have I tried Erythromycin.

If you find a magic cure, let me know!!

 

[JustOneMore20]

Looks like cyanobacteria to me as well. I've had some that is more brownish and dark green instead of blueish green.

Is it kind of slimy and wipes off pretty easily? If so, then its got to be cyanobacteria.

Increase flow, check your nitrates and if they are 5 or below, then I would add some KNO3. If you are dosing it now, then I'd up that a bit.

I have successfully knocked it out with Erythromycin (Maracyn). I only used a couple doses....even half the recommended dose a couple times tends to work. Just vacuum out the dead algae. That stuff is so nasty! But, its not too hard to get rid of it.

 

[fort384]

I had great success treating with Erythromycin. It knocked it out after about 4 days of treatment and has not returned. I also added a power head to increase flow, which probably helps to keep it at bay.

There are a lot of conflicting reports about the effectiveness of Erythromycin and whether or not it effects your biological filter. My personal understanding though is that BGA is a gram negative strain of bacteria, where as your biological filter is made up of gram positive bacteria. Erythromycin targets gram negative bacteria... any ammonia or nitrite spikes therefore are most likely caused by extra dead material floating around in the water after the BGA is killed off, and not because the antibiotic atacked your bio filter. That is a good reason to remove as much of it by hand as you can, and vacuum up the dead stuff as soon as practical during and after treatment.

However, there is some merit to the theory that overuse of Erythromycin without treating the cause of the problem (extra nutrients, low flow, even extra light as BGA is photosynthetic bacteria) could end up resulting in cultivation of a strain of BGA that could be resistant to antibiotic treatment, at which point you run out of options for total kill off of the BGA.