Pokeshell Farm

Pokeshell in the game are represented by one species. Their main property is to recycle polluted dirt and rot pile into sand (50% of what is consumed).

It is also a source of: Thus, the Pokeshell yields about 16 kg of lime.
 * egg shells (1 kg, at the birth of an egg),
 * small shell (5 kg, at egg hatch)
 * large shell (10 kg, at death).

I find Pacu Farm more interesting because it not only gives lime, but also meat. It's also more simple and doesn't require any dupes at all. Pokeshell farm will be useful on maps that don't have Pacu. Characteristics of Pokeshell
 * Feeds: polluted dirt and rot pile, 140 kg/cycle
 * Produces: sand 70, kg/cycle
 * Life span: 100 cycles
 * Reproduction rate: 5% (no grooming), 17% (with grooming)
 * Incubation rate: 5% (basic), 25% (incubator)
 * Minimum room size: 12 Cells/Animal
 * Temp: -15...+70°C

Description
The scheme consists of a closed farm of 96 cells, which is enough for 8 Pokeshell. All surplus eggs are removed from the scheme to the killing room (standard drowning room will not work). You can also wait until the egg incubates on its own and grows into an adult Pokeshell to get a small shell.

Pokeshell will attack the dupes if there are eggs within reach of the Pokeshell, so the grooming station is separated from the incubator by a door, although they are in the same room.

As always, the main difficulty arose with the incubator: the auto-sweeper and the dupes will put eggs into it, regardless of the "0" on the logical port or the power availability of the incubator.

It is useless to put an incubator on a mechanized airlock - the auto-sweeper will put an egg in it, because the door does not open instantly. So when the total number of eggs and Pokeshell in the room = 8, the mechanized airlock closes, blocking the auto-sweeper access to the incubator.

When the 9th egg appears in the room, the dupes has time to intercept the task of moving the egg from the floor to the incubator and the auto-sweeper cannot take it out of the circuit. Therefore, when the 9th egg/crab is born, the entrance to the scheme for the dupes is blocked and then the auto-sweeper puts the extra egg into the loader.

The rest of the circuit is simple. The bottom conveyor feeds the polluted dirt to the chute where some water is spilled (5kg is enough). Loader takes out of the circuit everything but the polluted dirt. The top door is set to exit only, so that the dupes is not accidentally trapped inside. Prioritize the incubator just above the loader (e.g. 6), so that the desired eggs are placed in it first.

Critter sensors: left <8, right <9.

Big Option
The farm consists of a stable (left room) measuring 96 cages, a room with 2 incubators, and a small stable measuring 12 cages.

All eggs are transferred to the incubators and wait there for their turn. The hatched Spawn, dupes are transferred either to the stable enclosure if the number of crabs there is less than 8 or released here. The critter sensor opens the door, and after a Spawn gets in the door, it closes it - the Spawn falls down.

In the lower room it matures, a small shell falls off it, gives birth to 1 egg, lives the rest of its time and dies and gives another large shell.

In this scheme, I did not submerge the polluted dirt with water, as in the first version. Crabs produce sand, just needed for deodorizers, and it would be logical to place them here. With enough polluted dirt, the deodorizer will be able to provide oxygen to the dupes in the scheme.

Settings

 * Left Conveyor Loader: eggs only
 * Right Conveyor Loader: everything except eggs and polluted dirt
 * Critter sensor: >0 (counting only animals)
 * Cycle Sensor: green - 15%; red - 20%
 * Timer Sensor: green - 20 s; red - 100 s
 * Critter Drop-Off: max. 8 animals. The left one has a higher priority of 6.

A Timer Sensor is needed to ensure that more dirt is coming in on the lower truss than on the main farm. Cycle Sensor is needed to save power. Its purpose and setup were described here

Summary
Over 170 cycles, the Crab population has reached 140 and continues to increase. In 1 cycle, the farm produces:
 * Sand kg
 * Shells (lime) kg
 * Clay kg and some oxygen

The consumption of polluted dirt is 4900 kg, which is a lot. You can reduce your dirt consumption by a factor of ten by turning this farm into a half-starved farm, just like it was done in Shove Vole Farm.

Additionally, you can limit the population of the main farm once you reach the desired number of crabs. This is easily done by reducing the number of animals in the Critter drop-off.

You can also turn off the incubators at any time. Eggs will incubate naturally, which will only slow down the population growth. It is also possible to give up the grooming of the Crab. With at least minimal diet (1 kg per Crab, once every 10 days), the farm will maintain the already achieved population.

Or you can do the opposite - extend your farm to the right by adding incubators. This way you'll be able to train dupes, and your farm will grow faster.

Blueprint
Pokeshell farm

Pokeshell farm, mk2