How are the diffusers mounted inside the tank? What are the mounting or floor tolerances?

Diffusers can be installed directly on the tank bottom or elevated if required. Grit removal (if necessary) is actually easier when the diffusers are installed very close to the bottom. Diffusers attach to the same air header and should be leveled within ±2.5 cm (±1“) of each other. The diffusers should be level to ±0.6 cm (0.25“) along its length to ensure peak performance.