Name: Nutrafin Cycle Category: Biological aquarium supplement Company: Hagan Manufactured in: Canada Star rating: 2 stars Value: 2 stars Model: 4 oz Price: $9.95 Warranty: None Several months ago a friend gave me some guppies and an old 10g tank she'd had in storage. Aware of the deadly nitrogen cycle, I ran out and bought a bottle of this pricey but reassuring elixir. After all, the label says "allows immediate introduction of fish" and "immediately establishes safe biological aquarium environment", and I'm a sucker for the word "immediate". Nevertheless, the guppies patiently lived in a bucket for 3 days while I dosed the tank. Did it work? Well, I'm not a chemist, but if nitrites shooting up 2 weeks later like the space shuttle is considered a success, yeah. Large water exchanges several times a week helped to keep it within chartable toxic levels and slowed down the REAL cycle, but the guppies DID survive. My immediate reaction was "How?"