Black stuff in a friends tank

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A co worker has a tank and has black stuff growing in his tank. He does have fish in the tank but is just running his filter. Any ideas what is growing in the tank? He said the tank is in his basement with no sunlight getting to it. The kids play down there, so any light the tank receives is from the basement lights. I asked him to take some pics and to bring in some of his gravel if possible. He did say prior to all this he has cleaned the tank and gravel with bleach and water hoping it would stop the black growth.

[Regalblue]

Post the pictures when you can.

[Ron]

Post the pictures when you can.

x2.

At the immediate moment, my thought is that it's algae of some kind.

[Regalblue]

Post the pictures when you can.

x2.

At the immediate moment, my thought is that it's algae of some kind.

Yep, same here.

[danielratti]

Its bacteria actually they call it blue green algae. Grows in like a thick sheet of slime and can be removed but will just grow back if the conditions of the tank do not improve. Poor water quality or excess food or waste is the cause of it generally.

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I just proof read my post and I meant to say he doesnt have any fish in the tank. He is just running the filter

[Ron]

I just proof read my post and I meant to say he doesnt have any fish in the tank. He is just running the filter

Did he previously have fish in the tank or is everything in there brand new/freshly cleaned?

[rcombs]

tell the guests that their is a toilet upstairs, stop using the tank!!! 

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tell the guests that their is a toilet upstairs, stop using the tank!!! 

 

[four_by_ken]

I am thinking dirty tank also.

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I just proof read my post and I meant to say he doesnt have any fish in the tank. He is just running the filter

Did he previously have fish in the tank or is everything in there brand new/freshly cleaned?

Ron,
 He had fish at one time and they all died. He cleaned the tank out with a bleach and water solution. Once he finished cleaning the tank he refilled it and ran his filter until the black algae or whatever it is started covering the rocks and a few spot on the glass.

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As it turns out its not black more brown in color. Here is the pics.

[Ron]

That's Bacillariophyceae.

Also referred to as "diatoms".

Also incorrectly referred to as "brown algae".

Nothing to worry about IMO. I see it in my tanks from time to time. It's easy to wipe from the glass. For the gravel, just stir up the gravel every so often to help make it go away.

[breaktime]

That's Bacillariophyceae.

Also referred to as "diatoms".

Also incorrectly referred to as "brown algae".

Nothing to worry about IMO. I see it in my tanks from time to time. It's easy to wipe from the glass. For the gravel, just stir up the gravel every so often to help make it go away.

Thanks Ron I will let him know