Agree with your intuition. When I initially went thru the process of rinsing the "sand" I noticed after I was done the plastic bowl I used was extremely scratched! At that point, I began to wonder what effects the same "sand" had on barbels and passing thru the gills. The bag ...
Do you think the slag will damage the cory barbels or be inappropriate for the eartheaters? So far, I have not noticed anything. I had wanted the torpedo beach sand but, it was not available at the store I was at.
A question about substrate. I have some carib-sea tahitian moon sand in a tank...does anyone have experience with it? Is it okay for corydoras or will it damage their barbels?