Urinal Nu Bio Block - Each block lasts for up to 1000 flushes. The Nu-Bio Block™ is a drop-in bio-treatment for urinals. It eliminates urine smells by slowly diffusing a bacterial culture. It is completely biodegradable, Will not cause build-ups in drains and canalisations. Nu-Bio Block™ is entirely safe for environment and. Has a neutral pH. You only need 1 block per urinal per month!