Aqua Craft Inc 1 DROPâ„¢ COPPER SULFATE 1 DROPâ„¢ COPPER SULFATE Copper sulfate has proven to be the most effective cure for C. irritants/white spot and Oodonium/velvet for marine fish. Each drop brings a treatment or hospital tank to 0.15 ppm. This is the proper therapeutic dose. Check the level of copper every 48 hours. Maintain this level for a minimum of 21 days. 1 DROPâ„¢ is NOT CHELATED. It can be removed easily or allowed to dissipate naturally. Copper based medications are not recommended for use in invertebrate aquariums.