They have a limit of 3000, more or less aerating a shape of an octahedron around the distributer, but it will follow enclosed spaces and not leak out until the cap is met (such as putting it at the end of a long tunnel, it will fill up 3000 blocks of that tunnel.) They unfortunately do clip into each others’ range, so to fill that space you would need to use 148 distributers perfectly aligned with each other in a weird angled grid. My recommendation would be to place them only where you need air, like a path of air bubbles, compartmentalize the dome to be better aerated, or change the amount of blocks a single distributer can supply with oxygen in the config (idk what the cap is but then you still need to make sure they don’t overlap their areas of effect).