Minecraft wiki entry for Mob_farm, associated text: The Canal-Style System still suffers from the mobs freezing when outside a certain range around your character in Java Edition, and from the limitations of low population density caps in Bedrock Edition. Active Systems can correct that problem. One example is using Redstone and Dispensers filled with a Water bucket to flood the spawning grounds repeatedly, flushing all mobs into the channels to be transported to the grinders. Thus, the farm provides area for the mobs to spawn in, but does not rely on mob movement to get them into the grinder. Using this, one can omit the trapdoors needed for the other, passive designs.