kscans

Chapter 272 - Trial and Error II

"If I had to give it a title, I suppose it would be 'The Sunken Forest'."

Maytyl said this as she gazed at the aquarium, now with a touch of green. By the way, today she was wearing a one-piece dress, with a circular opening at the chest and lace on the turned-up cuffs.

"The fish swimming among the plants look like butterflies dancing. The fact that it's all underwater makes it even more fantastical."

Princess Lisabet nodded in agreement.

Plants taken from the pond had been added to the tank. There were two types of aquatic plants. One had bright green leaves like mugwort, and the other stretched deep green, spiraled ribbon-like leaves toward the surface. It had been a week since they were planted.

"It's literally an aquascape."

I was satisfied with their words. It was just as I had planned. Small fish swam between the green leaves and the stems that grew from the gravel. The scene floating in the water was certainly picturesque and fantastical. If I were to be greedy, I would want some red-leaved aquatic plants too, but in this world, red carries an inauspicious image. That's a marketing challenge.

"But, the tips of the leaves are starting to look dirty, aren't they?"

Maytyl pointed to a leaf that reached just below the water's surface. It was turning brown and had holes in places. The worst ones were torn, as if they had half melted. The one with spiral leaves seemed to be a type that propagated via runners, like strawberries, but the seedlings that had emerged from between the gravel were collapsing.

Just when I thought they had acclimated to the water and started putting out new leaves and offshoots, they seemed to skip growing and began to wither.

"It's probably a problem with the substrate."

I looked at the bottom of the tank. On closer inspection, the tips of the roots visible between the pebbles were starting to rot.

"Unlike the stream, that pond had mud at the bottom, didn't it?"

"You're as sharp-eyed as ever."

The difference between aquatic and terrestrial plants is their style of nutrient absorption. Terrestrial plants basically absorb phosphorus, potassium, and nitrogen from the soil through their roots. That's because those nutrients are only found there. If you plant them in gravel like in this tank, they would wither in an instant.

But for aquatic plants, the water that covers their entire body is dissolved with those fertilizer components. Nitrogen and phosphorus come from fish food being broken down by bacteria.

Some aquatic plants, like the hornwort common in medaka bowls, have almost no visible roots. If you cut a piece and toss it in a tank, it will just float and multiply. It doesn't need soil, or even gravel.

However, many aquatic plants won't grow well without putting down solid roots. This is especially true for the species that look most like proper plants, suitable for decorating an aquascape. Plus, soil and stone have different specific gravities. Looking at the roots, it was possible they were being damaged by the gravel or compressed by its weight.

"Wouldn't it work to take mud from the pond and spread it on the bottom... oh, no, that's a bad idea."

"Yes, the aquatic plants would probably grow with that. But there are a few problems. One is filtration."

Mud clogs things up. That means you can't secure enough surface area for bacteria to grow. It would also put a strain on Maytyl's screw.

"Next are aesthetics and the hassle of maintenance."

Mud is easily stirred up. Even if water changes and cleaning are minimal, it's a big burden. Since this is a product, that's a factor we can't ignore. In that sense, gravel is a fairly ideal substrate.

"You're right. I wouldn't want to see my screw stirring up mud. So, what's the plan?"

"We'll make a substrate that's lighter than stone, can retain nutrients, and is easier to handle than mud. Something in between gravel and mud. Princess Lisabet, you have pottery artisans, right... huh?"

My voice echoed emptily against the wall. Princess Lisabet, who had been right there a moment ago, was gone.

"The steward called for her a little while ago. She went back to work."

"Is that so. Come to think of it, she seems busier than when I first got here."

"That's because I told her something useful. She's been working with a pale face ever since."

"You told her something useful, and it made her turn pale?"

"Yes. The story I heard from Mia about the 128 gold coins."

"Oh, that..."

"Indeed. A perfect lesson for this small domain, isn't it?"

"......I suppose so."

I shifted my gaze from a triumphant Maytyl back to the aquarium. The glass reflected my own grim expression. Shaking my head, I made my way to Princess Lisabet's office.

"A pottery artisan, you say? Yes, of course we have them in the domain. But, as for a sufficient number..."

"No, one will be enough. I just need a corner of the kiln. There's something I'd like to have fired."

I showed him the brown pellets on a wooden tray. They were bits of clay I had shaped into small grains. Of course, their sizes were uneven, and their shapes were far from spherical. I had made them with the image of the akadama soil used in gardening in my previous world.

*

"Here is the finished product, but, are you sure about this, My Lord?"

A hand stained with clay hesitantly offered me the fired, imitation akadama, now a size smaller. Well, it was just soil. I could more than imagine his confusion at being asked to fire dirt.

I picked up a single pellet and squeezed it between my fingers. It didn't budge. I placed it on a stone on the ground, picked up a smaller pebble, and struck it. Naturally, it shattered. I could see the artisan's face turn pale.

"The hardness is sufficient. Thank you."

The artisan's eyes went wide as I offered him a silver coin, an Imperial one, as payment. For the record, my backup plan was to get some failed pottery, smash it, and use the pieces.

*

In the two-layered substrate, gravel on the bottom and the brown, fired soil on top, the same two types of aquatic plants as before had taken root.

"How interesting. You can see new buds sprouting from the roots in different places from the side."

Maytyl said. A runner was visible, tracing its way through the baked akadama right along the aquarium wall, with a new offshoot reaching up into the water from it.

"It's less a root and more of a rhizome, really."

The aquatic plants, which must have taken a liking to the new substrate, were sending out more and more runners. Judging by the vigorous vegetative propagation, with new shoots growing progressively taller the closer they were to the parent plant, it seemed they would soon fill the entire tank.

At this rate, they were probably absorbing a fair amount of nitrate too. All that was left was to pull out these plants as needed, which would have the same effect as removing nitrate from the water. Though now, potassium, which isn't in the fish food, would become deficient.

"It's strange how much more beautiful it looks than when I saw it before."

Maytyl said, watching the school of small fish swim through their paradise. Princess Lisabet also nodded.

"Yes, to think that such familiar fish could shine so much as the main characters of this aquascape."

The two women's eyes were sparkling. Come to think of it, in my previous world, tropical fish were supposedly an excellent tool for luring girls back to your home.

"I can see how this would sell as a product. I want one myself."

"For you it would just be a test subject, wouldn't it, Maytyl?"

"How rude."

"To think such a beautiful and mysterious scene could be seen right in one's room. I would like one as well."

"Of course, I'll leave this one as a product sample. However, it's still incomplete. If left as is, its beauty will be short-lived."

I said, looking at the corners of the tank and the surfaces of the plants. A faint haze was forming there, a promise of future collapse. The aquatic plants weren't the only vegetation that was thriving.

*

Another five days passed.

"Ugh. It's a shadow of its former self. ...The fish seem fine, though."

Maytyl said with a strained expression, looking at the tank now submerged in a greenish-brown haze.

"Well, this is what I expected."

When I put my hand in, slimy algae clung to it, and a grassy smell wafted from the surface. Through the murk, I could see the faint glint of fish scales.

Yes, it was algae, the nemesis of aquariums. Well, to be precise, it's not moss, but algae. Even though I was limiting the food, nutrients were continuously being supplied to the water, and the substrate was a nutrient-rich imitation soil. And the light source wasn't fluorescent bulbs, but the much stronger light of the sun.

The conditions were perfect for an explosive growth of algae. You could even say the environment was made for it.

"What are you going to do about this? You can't possibly remove it by hand, can you?"

Maytyl said with a look of despair.

"It's impossible for human hands. First, we'll cover the tank to block out the sunlight. As for the rest..."

I picked up a net. I would have to go to the pond one more time.

"It's time to deploy the biological weapons."