Well, my substrate experiment just keeps getting better (not).
Apparently the "green diamond" grit isn't a granitic based substrate at all but Nickel slag!!! Argghhh. A quick check on the
www.targetproducts.com website (which I should have done if it hadn't flown under the radar on me) tells me I have a metal based substrate with low to moderate toxicity to fish. It took me by surprise as I never thought that slag would look like that.
So... don't buy that stuff
