might have made a mistake I dont know if I can fix

[tang daddy]

I wasn't referring to the black sand but rather the black substrate which is larger granules, looks awesome!

[FitoPharmer]

If your worried about iron in your tanks, the one pet store I worked at had no less then a dozen rusting razor blades in their system when I finally cleaned out the entire thing. I doubt they had any effect on the tanks. When I removed them everything was the same.

[Nano]

well its volcanic sane so would it be iron? its hard to say what type of metal is in it.