What substance in granite rock would make your water turn brown?

I am switching a recently emptied tank to a rock tank. I acquired some rock that I believe are a form of Granite. I scrubbed the rocks in a water and bleach solution a then placed in the tank in a water and bleach solution. When I refilled the tank to begin the cycling process before bed it was clear. When I got up the next morning the water was rust brown. What would cause the water to turn brown? Would metal deposits in the rocks do this? Before I placed them in the tank I examined the rocks for metallic flecks and these didn't have any. I an currently switching decore and fish around and plan to move my lace rock up stairs to this tank. If it browns out after switching it to lace rock I know what the culprit is the substrate.

Thanks for any input.

Try soaking the rock in a bucket of hot water and leave it for 24 or so hours, if it goes brown you'll know it's the rock.

Did you put any wood in the tank? I think that is usually the culprit for brown water.

What's the substrate?

Their isn't any wood in the tank that is in the process of being sterilized. The substrate is a mix of soil master select and flourite red and black.

I'd bet almost anything it is the soil.

Lively said:

I'd bet almost anything it is the soil.

Click to expand...

I would have thought that to but the substrate is over a year old.

Hmm, did you disturb it significantly when you moved everything?

Is it a dirty brown or a brown that you can see through. If it was the substrate from disturbing mulm than it would just look dirty. If its leaching it would be like tea, coloring the actual water? Let us know.

Its tea colored. Soil master select is actually a a type of gravel that was supposed to be used in the grass on football and baseball fields to absorb water. However the planted tank community found out about it and began using it for its absorption properties. a 50 to 100 pound bag is about $13.00 at your local John Deer or Lesco store.
http://aquamaniacs.net/forum/viewtopic.php?t=26387

And no I didn't disturb anything.