Why kelp makes money
Kelp grows on its own, breaks in bulk when the bottom block is broken, and smelts into dried kelp that blocks up nine to one. That makes it dense to store and quick to sell, and unlike mob farms it needs no spawner, no mob cap management and no risk of the farm shutting itself off.
The economics are simple: one player-built layer is a trickle, twenty stacked layers is real income. Kelp farms are worth building tall, not wide.
The basic design
- Dig or wall off a water column at least 12 blocks tall, deeper is better, more growth per harvest cycle.
- Place a kelp plant at the bottom and let it grow up the column.
- Put an observer facing the top of the column, wired to a piston that breaks the lowest kelp block when the column reaches full height.
- Catch the drops with water flow into hoppers and a chest, or a hopper minecart under the floor.
- Feed the chest into a smoker array with a fuel supply to convert kelp into dried kelp automatically.
- Craft dried kelp into blocks before selling or storing, nine times the value per slot.
Scaling it up
- Repeat the column in a grid; chunk-load-friendly designs keep all columns inside the same loaded chunks.
- Use a single central hopper line rather than one per column, hopper count is what kills TPS-friendly builds.
- Add a bulk smoker bank; the smelting step, not the growing step, is usually the bottleneck.
- AFK inside the farm's chunk range so the columns keep ticking.
Hide it or lose it
An AFK player standing still is a beacon. Build the farm deep underground or under an ocean, never with a surface entrance, and keep your AFK spot separate from your stash so a raid on one doesn't reveal the other.
The stash designs in this library are made for exactly this: no visible entrance, no lighting leaks, nothing that shows up on a render.