Review on Premium Activated Carbon for Aquariums - MarineLand Diamond Media, 40-Ounce (PA0373) by Vanessa Garcia

Before you put this in your fish tank, take a strong magnet and pass it over this charcoal. Carbon is not magnetic at all and nothing should stick to a magnet. If this is the case then the iron and possibly other metals are mixed in with the carbon you purchased and this could be having a negative impact on your reef aquarium. I got this for my reef tank. I had to rinse the charcoal for quite a long time to get rid of the dust and I put them in 2 brand new mesh bags and put them in 2 of my 4 filter socks. I left it for a week and when I went to change my charcoal I noticed an orange stain (definitely rust) on the mesh bag that I put the charcoal in. The bag only touched the toes of my filter, so "charcoal" was the only possible source of iron. The magnetic test showed that all the carbon I had was magnetic, which shouldn't be! My leather corals started to look bad and my Duncan corals died. I checked my tank for heavy metals using the ICP test and it showed significantly higher levels of nickel, tin, iron and aluminum. Based on the rust on my charcoal bag and the timing of my coral decline, I attribute the increased heavy metal content to the metal in this "charcoal". I hope this is a rare contamination of this product but be careful with this material. If you buy this material, do a magnet test before adding it to the aquarium. Doesn't seem like the quality control is very good, or maybe they're trying to poison the tanks to sell extra products.