Active ingredient: Removes chlorine and chloramine; detoxifies ammonia, nitrite and nitrate (binder); non-acidic
How to use (from the label): 50 g size: 200 mg (included scoop) per 200 L for chlorine/chloramine, or per 50 L for ammonia. Other sizes: 1.25 g (1/4 tsp) per 1,250 L for chlorine/chloramine, or per 300 L for ammonia. Options: double dose for very high chloramine; up to 4x in a nitrite/nitrate emergency; half dose above 30 °C if chlorine/ammonia are low; better added to new water first
Careful: Temperature: Use a half dose above 30 °C when chlorine/ammonia are low. Storage: Don't pre-dissolve and store; it is not stable in solution
Never mix medicines unless the label says it is safe, and remove shrimp and snails unless the label says they are safe.
Examples you may see in shops: Seachem Safe. Not endorsements. Always follow the label.
5 facts checked with sources