Directions for Use (Packets): For best results, remove activated carbon or filter cartridge from filter and continue aerations. For each 10 gallons (38 L) of water, empty one packet directly into aquarium. Repeat dose after 24 hours. Wait another 24 hours then change 25% of the aquarium water. Repeat this treatment for a second time, for a total of 4 doses. Then make a final 25% water change and add fresh activated carbon or replace filter cartridge. Treatment may be repeated if necessary.