Aquasoil is a nutrient-rich, fired-clay substrate designed specifically for planted aquariums. You can find it for sale through aquarium specialty retailers, online stores, and some local fish shops, with prices ranging from around $15 for budget alternatives to $35 to $60 for premium Japanese brands like ADA Amazonia. Unlike plain gravel, aquasoil actively releases nutrients into the water column and root zone, provides the slightly acidic pH that most aquatic plants and soft-water fish prefer, and has a porous structure that beneficial bacteria colonize effectively.
This guide covers the different types of aquasoil available, what the major brands offer, how to set up and maintain a planted tank substrate, and when aquasoil is worth the cost versus when a cheaper alternative works just as well.
What Aquasoil Actually Is
The term "aquasoil" is both a general category name and a specific product name from ADA (Aqua Design Amano), the Japanese company that popularized the substrate type. Generically, aquasoils are fired granules of clay, peat, or volcanic soil that have been processed to be hard enough not to break down quickly underwater, while still being porous enough to support plant roots and host bacteria.
Most aquasoils share several characteristics:
pH buffering: They buffer water pH down toward the 6.0 to 7.0 range, which benefits most stem plants, carpeting plants, and tropical fish like tetras, discus, and Corydoras that come from soft, slightly acidic rivers.
Nutrient release: The substrate releases ammonia, potassium, and micronutrients into the water during an initial leaching phase that lasts 4 to 8 weeks after setup. This is why new aquasoil tanks require water changes of 50% or more daily for the first week, then tapering to every few days for several weeks.
Rooting structure: The granule size (typically 1mm to 3mm) creates gaps that plant roots navigate easily, unlike fine sand that compacts or coarse gravel that roots can't anchor in.
Color: Most aquasoils are dark brown to near-black, which makes fish colors pop visually and looks natural.
Major Aquasoil Brands for Sale
ADA Amazonia (Original and Amazonia V2)
ADA Amazonia is the benchmark that other aquasoils are measured against. The original formula (now labeled Amazonia V2) is a dark brown substrate made from proprietary Japanese volcanic soil. It's sold in 3-liter (about 6 pounds) and 9-liter bags. At roughly $35 for 3 liters and $55 to $65 for 9 liters, it's expensive compared to alternatives.
The Amazonia formula is known for excellent plant growth, reliable pH buffering down to about 6.0 to 6.8 depending on water hardness, and a robust initial nutrient release. The trade-off is the leaching phase: Amazonia releases ammonia aggressively for the first 2 to 4 weeks, requiring significant water changes and typically preventing you from adding livestock for at least a month.
The 9-liter bag covers approximately 12 square inches at a 3-inch depth, which is enough for a 20-gallon tank.
Fluval Stratum
Fluval Stratum is made from volcanic soil from the slopes of Mount Aso in Japan and is one of the most readily available aquasoils in the United States and Canada, sold at PetSmart, Petco, and online broadly.
A 4.4-pound bag (roughly 2 liters) costs around $15, and a 17.6-pound bag runs about $40. Per liter, it's considerably cheaper than Amazonia. The plant growth performance is comparable to ADA for most common plants, though some advanced hobbyists report that Amazonia performs better for demanding carpeting plants like Hemianthus callitrichoides (HC Cuba).
Fluval Stratum buffers pH similarly to Amazonia and has a moderate initial ammonia release that's less aggressive, making the cycling period somewhat shorter.
Seachem Flourite and Flourite Black
Seachem Flourite is technically a different category than volcanic aquasoil. It's a porous clay gravel that doesn't buffer pH and releases nutrients more slowly and for a longer period than active soils. The trade-off is that it lasts indefinitely without exhausting (active soils lose their buffering capacity after 1 to 3 years and need replacing), and it can be used in tanks with fish that prefer neutral to alkaline water.
Flourite Black, at around $20 for 15.4 pounds, is a cost-effective substrate for planted tanks that don't need pH adjustment. It doesn't require the heavy water change regimen of active soils.
UNS Controsoil
UNS (Ultum Nature Systems) Controsoil is a premium aquasoil from Taiwan that competes directly with ADA Amazonia at a similar price point of $30 to $50 depending on bag size. Controsoil buffers pH reliably, has excellent granule hardness (good granule integrity after 18 to 24 months), and is available in two sizes: normal (3mm to 5mm) and powder (under 2mm).
The powder size is particularly good for foreground carpeting plants because smaller granules allow fine-rooted plants like Glossostigma and Monte Carlo to anchor quickly.
Tropica Aquarium Soil
Tropica is a Danish aquarium plant company whose substrate is derived from natural peat and clay compounds. It's available in 3-liter and 9-liter bags at $25 to $45 depending on size. Tropica Aquarium Soil buffers pH to the 6.0 to 7.0 range and has a modest initial nutrient release. It's especially popular in Europe where it's widely distributed.
For a broader comparison of substrate options including gravel and sand alternatives, see the best aquarium equipment roundup which covers substrates across different tank types.
How Much Aquasoil You Need
The standard depth recommendation for planted aquariums is 3 to 3.5 inches across the foreground, often deeper in the background (up to 4 to 5 inches) to accommodate larger-rooted plants.
Here's a rough guide to volume by tank size at 3-inch depth: - 10-gallon (20x10 inch footprint): about 3 liters - 20-gallon long (30x12 inch footprint): about 5 to 6 liters - 40-gallon breeder (36x18 inch footprint): about 9 to 10 liters - 55-gallon (48x12 inch footprint): about 9 liters - 75-gallon (48x18 inch footprint): about 13 to 14 liters
Buying slightly more than you calculate is worthwhile. Running short during setup means buying another bag, and different bags may vary slightly in color lot or granule texture.
Setting Up a New Aquasoil Tank
Rinsing (or Not)
ADA Amazonia and most premium aquasoils should not be rinsed before use. Rinsing removes the fine particles that fill gaps between granules and compromises the substrate structure. Dust that clouds the water after filling will settle within 24 to 48 hours with the filter running.
Cheaper aquasoil alternatives and Fluval Stratum can be rinsed briefly if you want faster clarity, but it's not required.
Layering with a Base Layer
Many serious planted tank hobbyists add a layer of nutrient-rich base fertilizer or lava rock under the aquasoil to extend the substrate's productive lifespan. Products like Brightwell AquaticsBacto-Reef or ADA Power Sand (a base layer specifically designed to go under Amazonia) add organic material that feeds roots after the active soil's initial nutrients exhaust.
For most beginners and intermediate hobbyists, a straight layer of aquasoil without a base layer works well for 12 to 18 months before requiring supplementation via root tabs or liquid fertilizers.
The Cycling Phase
With ADA Amazonia, expect an ammonia spike to 2 to 8 ppm during the first week. Do 50% water changes daily for the first week, then 50% every other day for the second week, then 30 to 40% every few days in weeks three and four. By week 4 to 6, ammonia should read below 0.25 ppm and the tank can be considered cycled enough for livestock.
Seeding the filter with bacteria from an established tank (running the new filter on an existing tank for two weeks, or using a bottled bacterial supplement like Seachem Stability or Dr. Tim's Aquatics One and Only) accelerates the cycling process significantly.
For substrate options and how they pair with different filtration setups, the top aquarium equipment guide covers the full equipment context.
When Aquasoil Is Worth It vs. Cheaper Alternatives
Aquasoil is worth the cost for: - Carpet plants and stem plants that require soft, acidic water - Softwater fish like discus, Apistogramma, cardinal tetras, and blackwater species - Any tank where you want a natural-looking dark substrate that supports roots actively - Dutch-style or Nature Aquarium-style planted tanks
Aquasoil is overkill for: - Fish-only tanks with no live plants - Goldfish tanks (goldfish destroy planted tanks anyway) - Tanks where pH 7.0 to 8.0 is required (African cichlids, livebearers, rainbowfish) - Very large tanks where the cost of 20+ liters of premium substrate becomes prohibitive
FAQ
How long does aquasoil last before needing replacement? Active buffering capacity typically exhausts after 1 to 3 years depending on brand and how heavily planted the tank is. After that, pH may creep up toward neutral. You can extend the substrate's useful life by adding root tabs and liquid fertilizers, but many hobbyists break down and resubstrate their planted tanks every 2 to 3 years as a matter of course.
Can I add aquasoil to an established tank with fish? Yes, but it's disruptive and the ammonia leach from new aquasoil will spike in an established tank. The safer approach is to either do a full tank reboot (remove fish, resubstrate, cycle, reintroduce fish) or add the aquasoil in a separate tank before combining.
Does aquasoil compact over time? Yes. After 1 to 2 years, the granules compress and the substrate loses some of its air pockets. This is normal and not a major problem for established plant root systems. In early stages, avoid overly deep substrate compaction by not pressing down when planting.
Can I use aquasoil in a shrimp tank? Yes, and it's actually ideal for neocaridina and caridina shrimp, which prefer slightly acidic, soft water. Caridina species like crystal reds specifically thrive in the pH 6.0 to 6.8 range that Amazonia and similar soils provide.
Key Takeaways
For planted aquariums with soft-water fish or demanding plant species, quality aquasoil like Fluval Stratum (budget-friendly) or ADA Amazonia (premium) is worth the cost and setup complexity. Fluval Stratum is the most accessible mid-range option that balances performance and price. Budget for the extended water change regimen during cycling, especially with ADA products. For fish-only tanks or setups where neutral to alkaline pH is required, Seachem Flourite or plain gravel is more practical. Buy slightly more substrate than you calculate; running out mid-setup is a common and avoidable frustration.