I need fertilizer for my planted tank but have been afraid to buy anything that would hurt my snails. Today at Petsmart I read all the labels and ended up buying API Leaf Zone. I did not see copper listed in the ingredients. Is this okay? This will only benefit plants that absorb nutrients through the leaves, correct? Will I still need to get root tabs for the root plants? Or will the snail waste in the substrate be enough? Also, what is "melting"? I've seen this word mentioned a lot.