Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
The smell you describe makes me think of BGA, too. Earthy, but stronger, and not as pleasant as the natural, earthy smell that I find in my tanks. I need to get really close to smell it, too. The smell from BGA is stronger, easier to notice.
I would get the NO3 up closer to at least 10 ppm.