The successful blasting trial had revolutionized the mines, but it had introduced a lethal imbalance into the barony's biological engine. To produce the black powder, Kael required concentrated nitrates—a chemical he was stripping from the waste-processing cycle of the aquaculture vats. For months, the system had operated in a delicate "Closed Loop": the fish produced ammonia, the bacterial filters converted that ammonia into nitrates, and the greenhouses used those nitrates as fertilizer.
By diverting the nitrates for munitions, Kael had effectively starved the Great Greenhouse and allowed the toxic ammonia levels in the vats to spike. The "grit" of this chapter was the smell—the pungent, eye-stinging odor of a biological system in collapse.
Kael was woken at midnight by Healer Mara. "The vats are turning," she said, her voice tight with exhaustion. "The silver-fin are surfacing, gasping for air. If we lose the fish, we lose thirty percent of our protein. The math of survival is failing, Kael."
Kael rushed to the aquaculture tiers. Through his optics, he could see the chemical reality: the water was becoming opaque, a sickly yellowish-green. The bacterial colonies in the sand-filters, overwhelmed by the sudden shift in the nitrogen cycle, were dying off in massive sloughs. Without the bacteria to process the waste, the ammonia—a potent neurotoxin for the fish—was reaching lethal concentrations.
"The system is suffocating on its own success," Kael realized. He had optimized for gunpowder but forgotten the biological latency of the vats. He couldn't just "turn off" the ammonia production; the fish were alive and breathing. He had to engineer a Rapid Bio-Augmentation.
He initiated the Charcoal-Scrub Emergency. He ordered the "Information Citizens"—the telegraphers—to use their high-speed network to call for every scrap of activated charcoal from the kilns. This charcoal was packed into perforated iron crates and dropped directly into the water channels. Activated charcoal could chemically bond with the ammonia, buying the system a few hours of time.
But this was a patch, not a cure. The long-term solution required more surface area for the nitrifying bacteria to grow. Kael looked at the thousands of tons of limestone rubble produced by the recent blasts. Limestone was porous. It was the perfect substrate.
"Hektor, I need the rubble teams!" Kael shouted over the roar of the water pumps. "We're not hauling this stone to the kilns. We're hauling it to the vats. We're building Biochemical Trickle-Towers."
Under the flickering light of oil lamps, the Aspirants and the new penal-laborers performed a frantic, wet labor. They constructed three-story-high towers of iron mesh, filling them with the porous limestone rubble. Water from the vats was pumped to the top and allowed to "trickle" down over the stones, exposing it to the air and the new bacterial colonies Kael was desperately trying to culture.
The social cost was high. To power the additional pumps for the trickle-towers, Kael had to divert steam from the Iron Works. This meant the assembly line for the Imperial Axles ground to a halt. The "Old Citizens" were furious; they saw their productivity bonuses vanishing to save a "tank of stinking fish."
"Is an axle worth more than your dinner?" Kael challenged a group of grumbling smiths. "If the vats fail, we spend the next six months eating nothing but tuber-paste and grit. You want your bonus? Pick up a basket of stone and move it to the towers."
The technical failure occurred at the four-hour mark. The sudden weight of the wet limestone towers caused the timber supports of the secondary vat-tier to groan and shift. If the tier collapsed, it would create a domino effect, destroying the entire aquaculture complex.
Drax, the former mercenary turned blasting-foreman, didn't wait for a command. He dove into the waist-deep, ammonia-tainted water with a heavy iron jack, bracing the shifting timber with his own strength until the team could bolt a permanent iron sleeve into place. His skin was blistered by the chemical water, but he held the line.
By dawn, the ammonia levels began to stabilize. The "Trickle-Towers" were working; the increased oxygenation and surface area allowed the bacteria to recover. The silver-fin stopped surfacing. The biological heart of Ashfall was beating again, but it was now a much larger, more complex beast.
Kael stood atop the highest trickle-tower, looking out at the barony. He had saved the food, but he had learned a hard lesson in Industrial Interdependence. You could not touch one part of the machine—the mine, the forge, the vat—without the vibration being felt in all the others.
"The loop is no longer closed, Elms," Kael said, his voice raspy from the ammonia fumes. "We are an open system now. We need more water, more stone, and more energy than this valley can provide. We've outgrown the barony."