Bubbles in aquarium water have multiple causes - some normal, some warning. Normal bubbles: 1) New water with dechlorinator - clears in 4-6 hours. 2) Filter return + powerheads create surface agitation - normal. 3) Plant pearling (CO2 oxygen bubbles in heavily-planted tanks during photosynthesis) - sign of healthy plant growth. 4) Cold water releasing dissolved gas as it warms in tank. 5) New tank degassing for first week. Warning bubbles: 1) Persistent foam on surface = high dissolved organic compounds (DOCs). Do 30% water change + run carbon. In reef tank, indicates overdue skimmer cup empty. 2) Constant micro-bubbles in tank = pump cavitation or sump intake drawing air. Inspect impeller seals. 3) Massive bubbles + cloudy water with foul smell = bacterial bloom + decaying organic matter. Immediate water change. Pearling vs problem: pearling stops a few hours after lights off; problem-bubbles persist. Surface tension film: oily slick + bubbles trapped underneath = protein film. Use surface-skimmer attachment on filter intake.
The full Q&A library, calculators, diseases, glossary, and interactive tools answer the most-searched aquarium questions.
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