Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Brown water like this, just a tint, is usually from the organic acids in the potting soil.
It may go on for a month or so, gradually getting lighter.
To make it go away faster you can do more water changes, and you could add Purigen or Activated Carbon to the filter.
It does block a small amount of the light getting to the plants, but if it is pale enough that you can still see into the tank then it is not blocking that much light.
I had some wood that make the water as dark red as red wine. Could not see into it at all! That is a bit much.