Bad Substrate??? | Cichlid Fish Forum
This material is slag from nickel and coal mining. It is not safe for use in aquariums. Not only will the iron particles destroy magnetic impellers, the high levels of heavy metals will dissolve in the water and be toxic to fish. The copper level is 0.2-0.4%. That's equivalent to 2000ppm. Dosage rate for copper treatments is generally 0.1 ppm.