

Black streaks/spots in sand
It’s a 3-gallon tank, and it’s been partially set up for about 2 weeks now. I’m having some issues with the plants I intended to add, so I won’t be able to add any for a couple more days. Anyway, this is my first attempt with a soil and sand cap, and I noticed these black spots on the surface and black streaks just underneath. I’m wondering if it’s a problem, and if so, how I can solve it.