Free Full Share by Nathan Lowell

collector plates and by the time we’d finished with number three’s frames and had them reloaded, the other ones were ready for us.
    Francis, Diane, and I started on number one scrubber while Brill consulted with Mr. Kelley. “We’re going to be desperately close, Fred,” she said. I didn’t like that she was calling him Fred. It meant things were really as bad as I had thought.
    “I know, B. We can add more oxygen, but we have to get rid of the CO2. How much calcium hydroxide do we have?”
    “About eight tons but how do we get enough air over it?”
    Calcium hydroxide was a natural CO2 absorbent. We kept a supply on board but I hadn’t been sure what we used it for. Now it all made sense. The problem was surface area.
    I kept slopping frames as fast as I could. Diane was pulling them out and handing them to Francis and I. We were pulling dying matrix out as fast as we could split the frames and we were darn fast.
    Brill was asking, “Can we rig up some kind of canister filter with it in it? Like they use on the little ships?”
    Mr. Kelley had his tablet out now and was running figures. “Too much air, the canisters would calcify into limestone too quickly. We need some way to expose as much surface as we can.”
    I finished stripping out the latest matrix and bent to stretch my back. “Spine!” I shouted.
    Diane handed me the next frame and I kept working as I talked. “The spine. It’s like a big straw.” I finished stripping matrix and tossed the empty frame into the wash me pile. Diane handed me the next one. “It’s only about two meters wide, but it’s five hundred meters long. Spread the calcium hydroxide on the floor, CO2 is heavier than oxygen and it’ll pool between the hatch combings. If the powder calcifies, we can scrape it up, put down more powder, and drop the limestone out the lock.” Diane handed me another frame.
    Mr. Kelley was running numbers.
    We finished stripping down number one and broke out the hoses to wash it all down before breaking out fresh matrix. We started laying down cleaned frames, Francis and I made them up, Diane sprayed them with new bacteria, and Brill hung them before he stopped running numbers.
    “It’s gonna get stuffy in here, but it might work. We need to increase flow or the CO2 will pool in the lower parts of the fore and aft sections.”
    Brill said, “Run a long exhaust duct from the life boat deck to the after section. Pull everybody you can out of there. Blow the air from the boat deck into the after section and let the pressure differentials bring the fresh air back. You can set up a little bit of circulation and keep the highest levels of CO2 running across the surface.”
    He added that to his calculations as we finished with number one. The problem was not in getting them rebuilt, it was the time it would take for the algae to bloom and begin scrubbing. We were shaving off a few valuable minutes by working quickly, but we were short by too many to make much difference if we couldn’t manage to control the overall CO2 levels.
    “Better,” he announced. “Might be enough.” He pulled out his comm, headed for the hatch, and was lining up people and equipment before he left the section.
    We just kept building frames. Diane latched the lid back down on number one and I looked at the chrono, 22:00. If I were still alive at 09:00, we’d probably make it.
    We started on number four and nobody talked. We just worked.
    By 23:30 we had all the scrubbers rebuilt, and settled down to check the numbers. CO2 was still climbing, but the engineering crew was still rigging the duct work. Some of the deck gang had been put to work spreading the calcium hydroxide on the deck along the spine. They were shooting for two, five-centimeter-deep strips along either side of the spine with about a half meter open area in the middle to walk on. It would take almost all the powder we had to cover that much space but it gave us a large surface area to stream the CO2 laden