The aquascape hardscape quantity guide calculates how much rock or driftwood to buy for your aquarium layout. Rock density varies significantly by type — Seiryu Stone (1.8 kg/L) is heavier than Dragon Stone (1.5 kg/L) or Mopani Wood. Enter your tank dimensions to get a recommended hardscape weight range.
Tank Dimensions
How to Plan Aquascape Hardscape
Hardscape — rocks and driftwood — is the structural foundation of an aquascape. Buying too little leaves you short mid-scape; buying too much wastes money on heavy rock. The 1–2 kg per 10L guideline is a starting point; your actual needs depend on the specific layout style.
Step 1: Plan Your Layout First
Sketch your composition before buying hardscape. Iwagumi layouts (rock-only, no wood) use the most stone. Dragon stone island layouts need 6–12 kg for a 60L tank. Mixed rock and wood scapes need less of each material.
Step 2: Choose Rock Type for Your Chemistry
Seiryu Stone raises KH and pH significantly — it can push a soft-water tank from pH 6.5 to 8.0+ over weeks. Dragon Stone raises pH minimally. Lava rock is inert. If you keep Caridina shrimp (Crystal Red, Taiwan Bee) that need soft acidic water, avoid calcite rocks entirely.
Step 3: Soak Before Use
Soak new rocks in a bucket for 3–7 days before placing in your display tank. This removes surface dust, leaches initial chemistry changes, and lets you check for sharp edges. Dragon Stone in particular benefits from a 3-day soak.
Step 4: Follow the Rule of Odds
Use an odd number of main rock pieces (1, 3, 5, or 7) for more natural-looking compositions. One large focal rock with two smaller supporting rocks is the classic Iwagumi triangle. Avoid symmetric layouts — nature is not symmetric.
FAQ
How much rock do I need for aquascaping?
A common guideline is 1–2 kg of rock per 10 liters of tank volume. For a 60-liter tank, plan on 6–12 kg of stone. The exact amount depends on your scape design — a mountain layout uses more rock than a simple island grouping.
How heavy is Dragon Stone?
Dragon Stone (Ohko Stone) has a density of approximately 1.5 kg per liter of stone volume. It's a relatively lightweight volcanic rock with excellent texture for aquascaping. It does raise pH slightly when new, so soak it before use.
How heavy is Seiryu Stone?
Seiryu Stone is a harder, denser metamorphic rock at approximately 1.8 kg per liter. It's heavier than Dragon Stone and significantly raises KH and pH — often to the point of preventing Caridina shrimp keeping without a large resin filter.
Does the rock raise my water hardness?
Yes. Seiryu Stone and similar calcite-rich rocks significantly raise KH and pH, sometimes beyond 8.0. Dragon Stone raises KH mildly. Test your water weekly after adding new hardscape. If KH rises above your target, limit the amount of calcareous rock.
Is this calculator free?
Yes, completely free with no signup required.
Does the calculator support metric and imperial?
Yes. Toggle between inches/centimeters for tank dimensions and the results show both kg and lbs for rock weight.