Aquarium Gravel Calculator — Substrate Weight in Pounds & Kg

The simple rule: 1 pound per gallon per inch of depth. A 30-gallon tank with a 2-inch gravel bed needs ~60 lb. For a more accurate calculation, use the calculator above and input your tank's actual footprint.

Fish-only: 1–2 inches. Planted tanks: 2–3 inches (4 inches if using root-feeding plants like swords). Too deep and anaerobic pockets form; too shallow and plants won't anchor.

Gravel — easier to clean, better for beneficial bacteria. Sand — more natural-looking, better for bottom-dwellers like Corydoras and loaches. Sand is heavier (105 lb/ft³ vs 100 for gravel) and can compact over time.

Yes. Pool filter sand is 110 lb/ft³, inert, silica-based, and much cheaper than aquarium sand. It must be rinsed extensively before use.

Planted substrates like Eco-Complete and Fluval Stratum are lighter (~60 lb/ft³) and typically sold in 9 lb or 20 lb bags. A 30-gallon planted tank with a 3-inch bed needs ~50 lb.

Pour 5–10 lb at a time into a clean bucket. Run water through until water runs clear (this takes 5–10 passes). Unrinsed gravel makes the tank cloudy for days.

Excessive depth (>4 inches) with no plant roots creates anaerobic zones that produce hydrogen sulfide (H₂S). Periodic gravel-vacuuming prevents this. Deep sand beds require burrowing species.