Aquascape Hardscape Weight Calculator

Estimate rock and driftwood weight, displaced water, and added floor load for safe aquascaping. Choose material types, coverage, and height to size your scape confidently.

Tank & Layout Basics
Rocks
Driftwood

Results

Usable Height
Tank height minus average substrate depth.
Rock Volume & Weight
Wood Volume & Weight
Total Dry Weight
Rocks + wood (in air).
Displaced Water
Volume taken up by hardscape.
Net Added Tank Load
Assumes constant waterline: add (ρ−1000)×V.
Floor Load Increase
Added load per footprint area (compare to ~40 psf / 195 kg/m²).
Tip
Spread weight with foam/egg crate; seat base rocks on glass, not atop loose substrate.

Hardscape Safety & Efficient Design

Spread Load and Protect the Glass

Place heavy base stones directly on the glass with a thin foam or egg-crate layer to diffuse point loads. Avoid balancing stones on small contact points over deep substrate.

Lock Structures, Don’t Stack Loosely

Use cyanoacrylate gel + cotton/fabric or epoxy putty to create stable interlocks between rocks and wood. Test for wobble before flooding.

Account for Displacement

Rocks and waterlogged wood displace water; if you keep the waterline constant, the net added weight is (material density − 1000 kg/m³) × volume. Porous lava rock adds much less net load than dense slate or granite.

Plan for Flow & Maintenance

Leave gaps around the foreground to prevent dead spots. Keep the tallest mass near a golden-ratio focal point and away from filter inlets/outlets to maintain circulation.

Typical Densities (reference)

  • Seiryu/Granite/Slate: ~2600–2750 kg/m³ (heavy)
  • Sandstone: ~2200 kg/m³ (medium)
  • Dragon/Ohko: ~1400 kg/m³ (light, porous)
  • Lava: ~900 kg/m³ (very light, porous)
  • Driftwood (dry): ~600–800 kg/m³; waterlogged approaches ~1000 kg/m³

Disclaimer

Estimates only. Always verify stand ratings, floor capacity, and local building codes for large tanks.

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