Brown Growth on Rocks & Sand

[ptrant]

I have a 70g tank that's a few months old and I recently noticed brown growth on the rocks and in the sand. Its almost copper colored and its spreading quickly...

I was told that it may be a sign that my lights are old but this doesn't seem possible considering the lights are new with the tank 2 months...
Any thoughts?

 

[cjason3041]

sounds like diatoms....but 2 months they should be gone??......what kind of lighting?

 

[ptrant]

Nothing special, Power Compact Lighting
I keep them on for four hours a day for the two fish in the tank

 

[cjason3041]

how long has the tank been set up...6 weeks or 2 months...and do you have a clean up crew?

 

[ptrant]

Six weeks may be right...I don't have a clean up crew just two fish.
I let the tank cycle for about a month and tested everything before I put any fish in the tank...
Will the brown go away as time passes?

 

[cjason3041]

it will go away, but a crew would help...diatoms are a natural, but anoying part of the cycling process...just because it is safe to put in fish doesn't mean everything is done....other stuff must cycle and grow, an aquariun is a little biosphere so to speak....next you might get some red algae that will be harder to get rid of FYI. a crew will help with all of this and patience, proper lighting (less during this phase will help, but it is still gonna happen) proper water flow, and oh yah.....something i have very little of, patience...so good luck on that one