Use 1 cup (240 ml) of for every 35 gallons (132 liters) of water. Carbon PLUS™ should be rinsed first in freshwater and then poured into a filter bag. Next place in your sump, filter or other part of the system. CAUTION – product will generate heat and fizzle when first wet – do not let contact skin. Will last about 6-8 weeks depending on tank conditions.