One of the most important factors in rebreather design is scrubber efficacy. It is also one of the least well-understood. Generations of rebreather divers have guessed at how long their scrubbers will continue to scrub carbon dioxide when using their equipment in environmental conditions outside of those in which they were tested... which is 99% of the time. Other users have incorporated personal use practices based on untested community lore and myths. This book dispels many of these unsafe practices and provides a base for making informed decisions regarding real-world diving practices vital for the rebreather diver.