Dennerle Carbo Care Bio is a daily biological carbon fertilizer for planted nano aquariums. All plants need a carbon source, it is their most important nutrient, and without it, plants grow poorly, and algae can take over. Using Dennerle Carbo Care Bio Daily is an easy way of supplying this. Hobbyists often use this type of product first, to see the benefits before switching over to an automated system. In some aquariums, especially with plants that have a slow nutrient take up, using this alone will see a marked improvement in plant growth.