Red Algae Growth in 90 gal community tank
 

We've got a growth of red algae in our 90 gallon community tank (gourami's, danios, barbs, cories, one silver dollar, etc) that doesn't seem to be going away. It's all over the substrate, rocks,and a little on the tank walls. We are currently keeping the lights off hoping that would kill it but doing some research I came across this:

EDIT 2: Red algae is not reliant on photosynthesis (it is cyanobacteria, not true algae), so it can live in almost total darkness (with strong lighting, the cyanobacteria is, as its name suggests, blue-green).

Has anyone else gotten this and been able to resolve it? If so, how? Thanks.....

I'd like to be sure of the algae you have. "Red algae' is often used for brush algae, also sometimes called Black Beard, although to me it looks very dark green, but apparently it is in fact red. It grows as tufts on wood and rocks, then on plant leaves and often on filter tubes and even heaters. It is difficult to remove, having to be grasped and pulled from the object (which in the case of plants usually tears the leaf).

Cyanobacteria is a greenish slime that covers objects and can be easily removed with your fingers. Not a true algae but generally classed with algae since the causes are usually similar.

Both occur when nutrients and light are sufficient (i.e., in excess for the plants or the aquarium biologically equilibrium). Ironically, cyanobacteria is said to be caused by low nitrates (as opposed to high nitrates for other algae) and low light, although the couple of times I have seen it in my tanks I had normal light and nitrates. Regular maintaince (weekly partial water changes, not overstocking, not overfeeding, adequate but not too much or too bright light) and good plant growth usually keep algae in check. Some is natural in any aquarium as in nature. Some aquarists think they should see no algae in their tank, this is unrealistic (not suggesting you do, just a comment in general).

Depending which it is, there are means of getting rid of it. Few fish will eat brush algae (I believe some have said the true Siamese Algae Eater will, at least when small...not sure), none will eat cyanobacteria. Shrimp may eat some algae, no experience myself. Ottos and plecos will (to my knowledge) not touch either.

I have a couple of times seen a small patch of cyanobacteria, I just remove it with my hand at the partial water change (or use a paper towel, it clings to it better if it is on plant leaves). If it is severe, anitbiotics will kill it off, some have used Maracyn [there is a thread on this forum from a while back]. But be warned, Maracyn will affect some plants, it has a biological effect even if the package may say it won't. I used MAracyn once for columnaris, and the pygmy chain swords and red-leaf swords and crypts literally melted (they grew back from the roots).

Brush algae I leave on wood and rocks; when it invades plant leaves badly I remove the leaf. Anubias frequently gets this. If it is out of control, using Seachem's Excel (a liquid carbon plant supplement) is successful in ridding the tank of it.

Byron.

Thank you for the suggestions!

I don't know what the nitrate levels are, FP does the water testing.....since I posted I did some further reading throughout the web and from that I think it is the beard algae. I also read (and FP mentioned it too) that using a low level chlorine [bleach] wash will kill the growth, but each plant, rock, etc has to be "washed" separately. LOL, oh I know no aquarium will ever be algae free, that's just a pipedream, but this is a new situation and having turned off the lights doesn't seem to have affected it. They've been off for several days now. We do have cories and a [bumble bee - ???] catfish in the tank, some nerites too, but they don't seem to be able to keep up with it. The tank used to be nicely planted but some of the plants we had in the tank have been depleted by the silver dollar eating away at them. Could the changes in plant life have contributed to it?

Learning, learning, learning.... :-D

To your question, yes, the plants would have been using light and nutrients, and when these are in balance in an aquarium the plants tend to utilize them before algae, which only takes hold when the light and/or nutrients exceed what the plants need. Having lost all the plants (yes, the SD do eat plants) there is then an increase of available light and nutrients, so algae steps in to use it.

However, this brush algae is controllable as I suggested previously. As you have no plants (it can kill them when it covers the leaves) I wouldn't be too concerned. It actually looks rather nice and natural on wood and rocks..but that's just my thinking. I only keep it off plants and I'm satisfied with a bit elsewhere. Try the Excel if you want to get rid of it; I know Aunt kymmie on here as had success with Excel, probably others have too.

Byron.

There are a few plants left in the 90 but not like it used to be. We'd hoped the nerites would make short work of it as they did the green algae that was present a while ago but they haven't had the same impact on this. Side note - watching the progress of those little buggers (and the Brigs in the other tanks) going at the algae is pretty cool!

I'll suggest the Excel to FP see what he wants to do.

Thanks again for the input! :thumbsup: