Substrate depth depends on tank type + plant or aesthetic goals. Fish-only freshwater: 1-2 inches of sand or fine gravel. Enough to look natural, easy to vacuum. Low-tech planted (anubias, java fern, crypts): 1.5-2 inches inert sand. Anubias + java fern attach to driftwood/rock anyway. High-tech planted (carpets, root feeders): 2-3 inches with aquasoil base + sand or gravel cap. Some scapes use 4-6 inches at the back to create slope. Reef tanks - shallow: 0.5-1 inch aragonite sand (CaribSea Special Grade, Fiji Pink). Easy to vacuum + high flow over substrate. Reef tanks - deep sand bed (DSB): 4-6 inches sugar-fine sand. Provides anaerobic denitrification at depth. Maintenance-intensive + crashes ugly if disturbed. Mostly out-of-favor for modern reef. Avoid the 2-3 inch reef trap: too deep for proper turnover, too shallow for anaerobic denitrification - anaerobic pockets release sulfide. Bare-bottom: SPS reef + breeder grow-outs. Pros: max waste removal, hot water flow. Cons: visually stark. Slope: shallow at front (1") + deep at back (3-4") for visual depth. Black diamond blasting sand is a budget alternative to expensive aquarium sand - inert, dark color, ~$15 per 50 lb at Tractor Supply.
The full Q&A library answers the most-searched aquarium questions. Browse calculators, glossary, and disease database for related help.
Whatever specific topic brought you here, four fundamentals govern long-term aquarium success: water quality, parameter stability, biological filtration, and species-appropriate husbandry. Skip any one and the others struggle to compensate.
Water quality: ammonia + nitrite at zero, nitrate under 30 ppm freshwater + 10 ppm reef. Test weekly with API or Salifert kits. Use our water parameter checker to score your readings against your tank type.
Parameter stability: stable wrong parameters beat fluctuating ideal parameters. Most fish tolerate a wide pH range if it's stable. Sudden swings of 0.4+ pH or 5+°F kill fish faster than chronic suboptimal values. Use temperature controllers (Inkbird) + automated dosing for consistency.
Biological filtration: the bacterial colony on your filter media + rock + substrate is the engine. Never replace all media at once. Use our filter turnover calculator to size correctly.
Species-appropriate husbandry: research adult size, territoriality, diet, and tankmate compatibility before purchase. Use our tank stocking calculator + compatibility guides.
How long does an aquarium take to set up? 4-6 weeks for full cycling + first stocking. Use our cycle ETA calculator + how long does cycling take.
What's the best aquarium for beginners? 20-gallon long. Big enough for parameter stability, small enough for budget + space. See beginner picks.
How often should I do water changes? 25-30% weekly. See water change frequency Q&A + water change calculator.
Why does my fish keep dying? 5 leading causes: uncycled tank, wrong species pairings, no quarantine, undersized tank, neglected water-change schedule. See full diagnosis.
Saltwater livestock · Freshwater livestock · Coral catalog · Care library · Q&A library (222) · Glossary (127) · Disease database (50) · Calculators (29) · Interactive tools (7) · Husbandry deep-dives · DIY projects · State legality directory