Please can you show me this calculation ? I don’t know why I think 5ml in 200l is 2.5ppmI think it very unlikely the iron killed fish. People lose fish all the time for unknown reasons. That said, this dose of iron was not intended for a marine tank and is much more than I would dose.
That product is 10,000 ppm iron. He dosed 5 mL per 200 l. So the dose was 0.25 ppm. I dosed my tank about 1-2 ppb, or a hundred times less.