# Black Algae?



## EnemyNSA (Jan 27, 2016)

So I removed a bunch of rocks from my tank recently and they're all covered in black algae-ish stuff.

The rocks were all originally a light gray-ish color, but almost all of the area exposed to light have turned very dark/black.

Here is a picture. The rocks had been out of the water for about a day and a half at this point.










The light color part of the rock at the top is because there was another rock on top of that, which also turned black. The bottom sides of the rocks are all normal color, so it's only areas exposed to light that changed color. The rocks closer to the light seemed darker than the ones near the bottom.

Some of the aquarium decorations/etc had black coverings as well (spots on the powerheads, a plastic skull turned half black, etc). However the gravel was not colored at all. There are no plants in the tank.

I tried to look it up and saw results for Black Brush/Beard Algae.. but almost all the topics revolve around planted tanks. Also something called a Cyanobacteria? But not sure if that is the same thing or what.

Suggestions? Tips & tricks? Since I removed the rocks I haven't seen it pop up again in the tank, but it was relatively recently. Would rather catch it early this time if it pops up again.

Thanks!


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## DJRansome (Oct 29, 2005)

It probably is back brush/beard algae. Control as you would any other algae...low nitrates and < 6 hours/day tank lights...no exposure to window sunbeams.

If it stays short...enjoy the natural look and don't worry about it.


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## EnemyNSA (Jan 27, 2016)

Yeah, my wife would leave the lights on from 8AM-11PM, Monday-Sunday.. I finally got her to start leaving them off during the day. The sun can't reach the tank at any point thankfully.

"Honey, the fish can see just fine without them on.."

Trying to just do afternoon/evenings now. I'll also double check nitrates.

On the rocks it covered it's really, really on there. Is there a good way to get it off? Medium scrubbing didn't seem to do much. Hose blasting it didn't either (don't have a pressure washer though). I have a generic plecostomus (maybe 8-9 inches now) but he/she doesn't seem to touch it.

It didn't get long or stringy though, so I guess that's good. I suppose I can live with the natural look on the rocks


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## tanker3 (May 18, 2015)

My light are only on a few hours a day. Just for me to see them and feed them. Fish do not need the light, unless the room in "pitch black".


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## Deeda (Oct 12, 2012)

You might want to try hydrogen peroxide to see if it can remove the stuff in the pores.

A self service car wash that has a hand held wand may also be an option to pressure wash the rocks using the water only option but be sure the wand is flushed of any soap residue. I used this method prior to buying a home pressure washer without any issues.


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## CeeJay (Aug 16, 2016)

One way that you can clean those rocks without having to scrub is to buy a bottle of excel and spray them let it sit for 10 minutes then you can put them back in the tank the algae will turn red and die. Cut your lights and feed less you have to much nutrition in the water. I take it this is a new tank?


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## EnemyNSA (Jan 27, 2016)

CeeJay said:


> One way that you can clean those rocks without having to scrub is to buy a bottle of excel and spray them let it sit for 10 minutes then you can put them back in the tank the algae will turn red and die. Cut your lights and feed less you have to much nutrition in the water. I take it this is a new tank?


It's been running for around a year and a half, though the black algae didn't start for quite a while. It didn't really bother me until I pulled everything out to do a full rescaping. Now I'm just trying to figure out a way to prevent it from happening again. I removed most of the rocks that were covered and didn't use them for the most recent setup, but I am sure there is some still in the tank.

I'll try excel.. reading about it, it seems like its supposed to help plants as well? What makes it kill off the algae?


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