How much gravel, sand or aqua soil do you need? Calculate the amount in liters and kg – including two-layer setups (nutrient soil + cap layer). Right here, no registration.
Gravel/coarse gravel/sand: density is around 1.4–1.6 kg per liter. Not a significant nutrient source, but stable and easy to clean.
Aqua soil / nutrient substrate: much lighter (about 0.6–0.7 kg/L) and supplies nutrients for plant growth, but usually also lowers pH slightly.
Two layers: a common aquascaping method: 3–5 cm nutrient soil at the bottom, topped with 1–2 cm of gravel or sand as a cap layer so the soil isn't visible and doesn't float up.
Practical setup tip: instead of fully covering the nutrient soil, first build a gravel border around the edges (especially at the front glass), then fill the soil into the resulting well in the middle. That keeps it hidden without needing a continuous cap layer.
Plan for reserve: round up the bag count on purpose with some buffer – for unevenness, a slope toward the back, or topping up later.
Instead of recalculating every time: your tank size and substrate type are saved in your profile – the tank setup assistant shows the right amount right when you add a new tank.
Set once (sand, fine/coarse gravel, soil, mixed) – available instantly for overview and future calculations.
Log every water change. Always see your history and last-change date at a glance.
Log pH, GH, KH, NO₂ and NO₃ after each water change – and see how they develop over time.
Get gross and net liters from your tank dimensions – including a deduction for substrate and decor.
Instantly calculate the RO/tap water mixing ratio for your next water change.
How many fish can your tank support? Check stocking density based on net volume.
How long does it take for the tank to reach the CO₂ target level after startup?
Footprint (length × width in cm) times the desired layer height gives the volume in liters. Multiplied by the material's density (e.g. 1.5 kg/L for gravel) gives the required weight in kg. Example: 100 × 40 cm footprint, 5 cm gravel = 20 L → 30 kg.
For unplanted tanks, 2–3 cm is enough. For planted aquariums, 5–8 cm is usually recommended so roots have enough grip and nutrients. Many people also slope the substrate slightly upward toward the back.
Gravel weighs about 1.5 kg per liter, coarse gravel about 1.6 kg/L, aquarium sand about 1.4 kg/L. Aqua soil (active substrate) is much lighter, about 0.6–0.7 kg/L – noticeably less weight at the same volume.
In planted aquariums, a nutrient-rich soil layer (aqua soil) is often used at the bottom, topped with a thinner cap layer of gravel or sand – so the soil doesn't float up and stays out of sight. Practical tip: instead of a continuous cap layer, build a gravel border around the edges (especially at the front glass) first, then fill the soil into the resulting well in the middle – keeping it hidden.
Depends on tank size, layer height and bag size. Calculate the amount in kg and divide by the bag size – the result is rounded up, since a little reserve for unevenness usually makes sense.
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