Brownish/Black Algae Growing on Holy Rocks..Why?

[immortality6000]

I have this algae covering a few pieces of my holy rock in my tank and am not sure the cause. It is a brownish/black(kinda unsightly). My local aquarium center told me that different lights produce different color algaes. Would much rather prefer a nice green over the rocks. Here are the pictures. Are levels off on something I don't know about?

 

[mike dunagan]

takes time to get green and long

 

[immortality6000]

Is that algae going to turn green? I was told that I should have green algae growing on the glass of my tank and I don't. I do my regularly weekly water changes and only feed once a day. I have about 30 fish in this 72 gallon tank. At the local pet shop he has a cichlid gtank that has a piece of holy rock that has a NICE bright green coating on the rock. Why is mine brownish/black?

 

[roombo]

how old is the tank

 

[Otherone]

So long as it just grows on the orniments not all over the glass it should be benifical algae and yes it will turn somewhat green not 100% nor get all stringy. I wouldn't be suprised if your Mbunas graze on it already. Also helps naturally create oxygen. If you think it's too unsightly you could always just boil it off but with cycled tanks it will probably just grow back.

 

[Muske]

How old is the tank?

How old are the bulbs?

I got undesirable algae when I was running Actinics as my dawn/dusk cycle. Since removing them, the brown algae is gone. What does the phosphorus look like?

 

[Knowdafish]

What kind of lighting do you have? How many watts total?

 

[Ash]

I dont know my lighting but its just the basic lighting you but at the lfs.. nothing fancy. I have the same alage. I also understand that its actually beneficial to the tank so I just left my alone.. it has not harmed my tank. I don't see my tank all day everyday though so it doesnt bother me. If you really want it gone I would try the boiling suggestion.