An aquascape substrate calculator tells you exactly how much substrate to buy based on your tank dimensions and target depth. Substrate weight varies significantly by type — ADA Aqua Soil is 0.9 kg/L, pool filter sand is 1.5 kg/L, and Fluval Stratum is 0.65 kg/L. Get the right amount before your next aquarium store run.
Unit System
How to Calculate Aquascape Substrate
Getting the substrate amount right before setting up an aquascape saves money and prevents the frustration of mid-project store trips. The formula is simple: tank footprint area × desired depth = volume, then multiply by substrate density to get weight.
Step 1: Measure Your Tank Footprint
Measure the inside length and width of your aquarium (not the outside glass dimensions). For a standard 20-gallon long tank, inside dimensions are typically 30 inches × 12 inches. Enter these in the calculator above.
Step 2: Choose Target Substrate Depth
Nature Aquarium and Dutch style: 3–4 inches (7–10 cm) in the back, tapering to 2 inches (5 cm) in front. Low-tech planted tanks: 2–3 inches minimum for root development. Most aquascapers use sloped substrate — use the average depth for calculating total volume.
Step 3: Select Substrate Type
ADA Aqua Soil is sold in 9-liter bags at approximately 0.9 kg/L. Fluval Stratum is lighter at 0.65 kg/L. Pool filter sand and standard gravel are around 1.5 kg/L. Denser substrates require more weight for the same volume.
Step 4: Add 10–15% Buffer
Always buy slightly more than calculated — substrate settles after filling, and some will shift during planting. A 10% overage is standard. The calculator shows the theoretical amount; add at least one extra bag for safety.
FAQ
How deep should aquascape substrate be?
For planted tanks, aim for 3-4 inches (7-10 cm) in the back sloping to 2 inches (5 cm) in the front. Low-tech tanks can use 2-3 inches. Dutch and Nature Aquariums typically use 3-4 inches for proper root development.
How much ADA Aqua Soil do I need?
ADA Aqua Soil has a density of about 0.9 kg per liter. Use this calculator to determine volume (tank footprint × depth), then multiply by 0.9 for kilograms. A 60×30 cm tank with 7 cm deep substrate needs about 12.6 liters = 11.3 kg of Aqua Soil.
What is the density of pool filter sand?
Pool filter sand has a density of approximately 1.5 kg per liter, making it heavier than ADA Aqua Soil (0.9 kg/L) or Fluval Stratum (0.65 kg/L). Sand creates a flatter, denser layer compared to porous volcanic substrates.
Can I mix substrate types?
Yes — many aquascapers use a base layer of coarse gravel or sand topped with nutrient-rich substrate like ADA Aqua Soil or Fluval Stratum. This reduces cost while keeping the active substrate in the rooting zone where plants need it most.
Is this calculator free to use?
Yes, completely free. No signup required. All calculations run in your browser.
Does the calculator support metric and imperial?
Yes. Toggle between inches/centimeters for tank dimensions and kg/lbs for substrate weight output. The calculator handles all conversions automatically.