It brilliant stuff...colours/odours/etc...it cleans them all out...plus you can recharge it, too. I never really measure how much I use, but use about the equivalent of a 250ml container for tanks up to 60 gallons, although Seachem suggests that amount is good up to about 200 gallons.
G. A. Christian Bilou, Herpetologist
Founder/Director, Reptile Rescue Alberta
Past-President, Calgary Aquarium Society