Best Seller | API Stress Zyme, 16 oz., 16 FZ Improves the development of the biological filter and helps clean a dirty aquarium. Contains over 300 million live bacteria per teaspoonful. Breaks down organic compounds that cause dangerous conditions such as ammonia and nitrite poisoning and low... ... more API Stress Zyme, 16 oz., 16 FZ Improves the development of the biological filter and helps clean a dirty aquarium. Contains over 300 million live bacteria per teaspoonful. Breaks down organic compounds that cause dangerous conditions such as ammonia and nitrite poisoning and low... Petco.com | | $16.18 go to store |