I've just been looking for different trace mixes and then thought to check what was in the one i was currently using. I've been using the garden direct trace mix for some time, which i thought contained high copper levels. However, after checking through some threads i think i've been using a different mix. This is the trace i've been using. It's contents are as follows: Boron 0.1% Copper 0.25% Iron EDTA 3.3% Magnesium 7% Manganese 3.0% Zinc 1.0% Molybdenum 0.005% It's a lot lower in copper than this trace mix. However it contains magnesium, which other traces recommended don't have. I've always dosed lightly as i thought it was high in copper. Although i haven't noticed any bad side effects from the magnesium (or higher manganese levels), does anyone know if this could be harmful to fish/shrimp if i start to dose at recommended trace levels?