The plants arrived. The soil was ready. The sand was rinsed. After weeks of planning, research, and anticipation, it was finally time to build our Walstad aquarium.
What followed was four hours of careful layering, planting, and water-adding that transformed an empty glass tank into the beginning of an ecosystem.
The Morning Prep
We started early, laying out everything we’d need:
- 20-gallon tank (cleaned and positioned on stand)
- 8 quarts of organic soil
- 20 lbs of pool filter sand (pre-rinsed)
- All our plants in buckets of dechlorinated water
- Tweezers, scissors, spray bottle
- A large plate for directing water flow
- Camera ready for documentation
The plants looked great—a bit travel-worn, but healthy. We separated them by zone and kept them moist while we worked.
Layer 1: The Soil
The foundation of Walstad is dirt. Not fancy aquarium substrate—actual organic potting soil. This provides:
- Long-term nutrients for plant roots
- Beneficial bacteria habitat
- Natural CO2 from decomposition
- A buffer against pH swings
We poured the soil into the tank and spread it to about 1-1.5 inches deep, slightly deeper in the back. The soil was dark brown, rich-smelling, and surprisingly exciting to work with. This wasn’t just substrate—it was the engine of our future ecosystem.
Pro tip: Remove any large sticks or debris. They’ll float up and cause problems later.
Layer 2: The Sand Cap
The sand cap serves several purposes:
- Keeps the soil from clouding the water
- Provides a clean look
- Anchors the plants
- Gives bottom-dwellers a nice surface
We carefully poured pre-rinsed pool filter sand over the soil, aiming for 1-1.5 inches. The key word is carefully—disturb the soil layer and you’ll have a murky mess.
Total substrate depth: 2-3 inches, sloping from about 2 inches in front to 3 inches in back.
The Planting Process
With substrate in place, the real work began. We followed our layout plan, working from back to front.
Background First
Amazon Swords (2 plants): These went into the back corners—one on the left, one on the right-center. We dug deep holes (2-3 inches) and buried the roots completely, with the crown just above the sand. These will be our focal points once they grow in.
Water Wisteria (9-15 stems): We separated the bunches into individual stems, stripped the bottom 2 inches of leaves, and planted them in three clusters across the back. The feathery foliage immediately made the tank look more alive.
Midground Next
Cryptocoryne wendtii (6 plants): These required the most care. We removed all the rockwool from the roots (this stuff doesn’t belong in a Walstad tank), rinsed thoroughly, and planted in two clusters. The tricky part: don’t bury the crown! Crypts rot if their growing point is underwater in substrate.
Java Fern (3 pieces): Here’s where the coral came in. We tied the Java Fern rhizomes to the coral using fishing line. In a few weeks, they’ll attach on their own and we can remove the line. The textured fronds against the coral looks beautiful already.
Foreground Last
Dwarf Sagittaria (15 plants): The carpet plants. We separated each tiny plant and used tweezers to insert them into the substrate in two rows across the front. Spacing was about 2-3 inches apart—they’ll fill in via runners.
This was tedious work, but the grass-like effect was immediate.
The Water Fill
Filling a Walstad tank requires patience. Pour too fast and you’ll stir up soil, destroy your work, and create a brown murky nightmare.
Our method:
- Place a large plate on the substrate
- Pour water slowly onto the plate
- Let it overflow gently across the tank
- Stop periodically to check for soil disturbance
Even with care, the water turned cloudy. This is normal! The fine particles settle within 1-3 days. We reminded ourselves not to panic.
The Floating Plants
Last step: Red Root Floaters. We rinsed them gently, removed any dead leaves, and floated them on the surface. We aimed for about 30-50% coverage, leaving open water for gas exchange.
Equipment Setup
With the tank filled, we installed:
- 75W heater: Positioned vertically near the bottom, set to 75-76°F
- Hygger light: Centered over the tank, set to 8-10 hours on a timer
No filter. This is Walstad, after all—the plants are our filtration.
First Impressions
Standing back, we looked at what we’d created. The water was cloudy (expected), but through the haze we could see the beginnings of an underwater forest:
- Tall Wisteria stems reaching upward
- Amazon Swords spreading their leaves
- Crypts clustering in the midground
- A carpet of tiny Dwarf Sag across the front
- Red Root Floaters dotting the surface
- Our coral centerpiece with Java Fern attached
It wasn’t perfect. Some plants were a bit crooked. The Wisteria looked sparse. The carpet had gaps. But it was ours, and it was alive.
The Waiting Begins
With setup complete, we entered the most challenging phase: waiting.
The tank needs to cycle. The plants need to adjust. Some will melt. Some will grow. The water will clear, then maybe cloud again. Bacteria will establish. The ecosystem will stabilize.
All we can do is:
- Keep the light on 8-10 hours
- Monitor temperature
- Test water in a few days
- Resist the urge to mess with things
Our first water test is scheduled for Day 3. Until then, we wait and watch our underwater world begin to come alive.