Walstad 10 Gallon No Filter Setup Guide
Diana Walstad’s ecological method turns an aquarium into a miniature pond where plants do the filtration that a canister would otherwise handle. A properly built walstad 10 gallon no filter setup runs silently, costs nothing to maintain monthly, and reaches ecological equilibrium within 8-12 weeks. This guide from Gensou Aquascaping at 5 Everton Park walks through the soil choice, plant density, fish stocking and the half-dozen small decisions that separate a thriving Walstad tank from a muddy disaster. No filter, no CO2, no fertiliser, just biology doing its job.
The Walstad Principle
Plants absorb ammonia directly, outcompete algae for nutrients, and release oxygen into the water column during daylight hours. A heavily planted tank can therefore process fish waste without a mechanical filter, provided the plant mass is sufficient and fish density stays low. The method works in tropical climates like Singapore particularly well because ambient temperatures suit most plants year-round.
Tank and Light Selection
A standard 10-gallon (37 litre) rectangular tank at 50x27x30 cm is ideal. Rimless looks better but rimmed tanks work equally well. Lighting needs to be moderate, not intense: a 15-20W LED at 6500K for 6-8 hours daily. Too much light triggers algae; too little stunts the stem plants that drive nutrient uptake. A $40 Chihiros A-Series or similar nano light handles the job without wasting wattage.
Soil Layer Build
The foundation is 2-3 cm of organic potting soil, mineralised by soaking and drying three times over two weeks. Miracle-Gro Organic Choice works but avoid any soil marked with added fertiliser or moisture crystals. Cap the soil with 3-4 cm of inert sand or fine gravel at 1-3 mm grain size. The cap prevents soil from clouding the water column when plants are disturbed during trimming.
Plant Density and Species
Plant heavily from day one. Walstad specifically recommends 80% of the substrate surface planted at startup. Mix fast-growing stems (Hygrophila polysperma, Ludwigia repens, Cabomba caroliniana) with slower foreground species (Cryptocoryne wendtii, Echinodorus tenellus). Floating plants like frogbit or Salvinia are essential; they shade the tank, consume ammonia fastest and indicate nutrient excess through rapid growth. The plant selection in our aquascape low light no co2 guide aligns well with Walstad principles.
The No-Filter Circulation Question
Strict Walstad uses no pump at all. Some keepers run a small sponge filter purely for flow, which the method tolerates. In a Singapore HDB unit where ambient ceiling fans create minor surface agitation, a truly filterless tank works provided floating plants are kept thinned to allow oxygen exchange. If the tank sits in a closed room with no air movement, add a sponge filter at a minimal flow rate to prevent surface film stagnation.
Cycling a Walstad Tank
Traditional fishless cycling with pure ammonia does not apply; soil already contains organic nitrogen and releases ammonia for the first 2-3 weeks. Run the tank plant-only for 4 weeks before adding fish. Expect diatoms, green water and surface scum during this phase; they resolve naturally as the plant biomass stabilises. Our aquarium cycling with plants piece covers the biology in more depth.
Fish Stocking Limits
Understock by 50% compared to a filtered tank. A reasonable 10-gallon Walstad holds 8-10 small tetras or rasboras, or a single male betta with a small snail cleanup crew. Avoid active waste producers like goldfish or cichlids. The low bioload keeps nitrate below 10 ppm indefinitely without water changes, which is the whole point.
Maintenance Rhythm
Top up evaporated water with dechlorinated tap, but skip water changes for the first 6 months. After that, change 10-20% every 2-3 months to replenish trace elements. Trim stems weekly to prevent shading the lower plants. Remove dead leaves promptly; soil decomposition plus dead plant matter creates hydrogen sulphide pockets that spike during disturbance.
Singapore-Specific Considerations
PUB tap water carries chloramine that harms soil bacteria as well as fish. Dechlorinate with Prime or Seachem Safe at dosing strength for both chlorine and chloramine. Ambient 28-32°C year-round means no heater needed; Cryptocoryne and floating plants relish the warmth. Electricity cost for lighting alone sits around $2-3 per month at SP Group tariff of $0.32 per kWh, making Walstad the cheapest tank format per litre you can run.
Troubleshooting the First Three Months
Diatoms in week 2-3 are normal; they disappear once nitrate drops. Surface scum indicates poor gas exchange; add floating plants or thin them if already present. Cloudy water past week 4 suggests insufficient plant mass; add more stems. If ammonia stays detectable past week 6, the plant biomass cannot keep up and you need to reduce stocking or add a small filter. Our beginner planted tank mistakes guide covers the crossover pitfalls.
When Walstad Fails
Tanks with high fish stocking, low light or soil capped too deeply starve the plants or overwhelm their uptake capacity. High-tech planted tank keepers sometimes find Walstad frustrating because the method rejects CO2 injection and dosing regimes. If you want fast growth and lush red plants, Walstad is the wrong method; if you want a quiet, self-sustaining ecosystem, nothing else comes close.
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Still Have Questions About Your Tank?
Drop by Gensou Aquascaping — most walk-in questions get answered in under 10 minutes by someone who has set up hundreds of tanks.
5 Everton Park #01-34B, Singapore 080005 · Open daily 11am – 8pm
