Kelp Farm (Four Basal Observers) in Minecraft

Four independent underwater observer modules harvest the first kelp regrowth. Opposing surface streams carry floating drops into a central hopper collector.

Each observer watches a retained bottom kelp block. In Java, growth changes that block from kelp into kelp_plant, triggering the observer without waiting for a third segment. Its rear strongly powers a stone brick with isolated redstone dust above; the dust activates the piston beside it, one block above the observer. The piston removes only regrowth. Four modules are spaced apart so each dust cross points into its piston. Drops rise through source water into two opposing surface streams and reach the exposed central 2x2 hopper collector. This original adaptation uses documented mechanics rather than an exact tested creator schematic.

Materials

• 73× Stone bricks
• 4× Sand
• 119× Glass
• 4× Observer
• 4× Kelp
• 50× Water
• 7× Hopper
• 1× Chest
• 4× Redstone wire
• 4× Piston
• 4× Sea lantern
• 4× Redstone
• 4× Kelp
• 2× Water bucket

Build steps

1. Build the tank floor: Build the y=0 foundation, using sand under the four planting positions x=1,4,7,10 at z=3. Coordinates are zero-based; z increases south.
2. Install the central collector: Build the four rear support bricks at (1,1,1), (4,1,1), (7,1,1), and (10,1,1). Assemble the central hoppers and chest exactly as shown.
3. Enclose and light the tank: Build the glass tank walls and roof, with four sea lanterns in the side walls. Keep all four planting columns and the central hopper tops unobstructed.
4. Install the basal detectors: At x=1,4,7,10, place an observer at (x,1,2) facing south toward the planting base, and a piston at (x,2,2) facing south toward the first regrowth position.
5. Wire each independent module: Put one redstone dust on each support brick at (x,2,1), with x=1,4,7,10. Leave the dust crosses isolated and pointing toward the adjacent pistons.
6. Fill the tank and surface streams: Fill every shown lower water cell at y=1..2 with source water. At y=3, place sources only at x=1 and x=10 for both z=3 and z=4, making two opposing streams toward the central hoppers.
7. Plant the retained kelp bases: Plant kelp only at (1,1,3), (4,1,3), (7,1,3), and (10,1,3). These four bases stay underwater and survive every piston harvest.
8. Check harvesting and item transport: Wait for natural growth. Check that each piston retracts, its bottom kelp survives, and floating drops reach the central hoppers and chest.