All aquariums have some algae - the goal is balance, not zero. Common types: 1) Brown diatoms (silica-fed, common in tanks under 4 months, otocinclus + nerite snails clear it). 2) Green spot (high-light, low CO2 - normal on glass + slow plants). 3) Green water (single-cell algae bloom, UV sterilizer or 3-day blackout). 4) Hair / thread algae (high-light + low-CO2 imbalance, manual removal + amano shrimp). 5) Black beard (BBA - low CO2, high organics; spot-treat with Excel/Easy-Carbo). 6) Cyanobacteria red slime (low flow + high organics + low nitrate; ChemiClean or Maracyn). Root causes: too long photoperiod (cap at 8h), direct sunlight (move tank or curtain), overfeeding (more food = more nutrients = more algae), uncycled tank, no plants competing for nutrients, dirty filter, low flow areas. Algae crew: nerite snails (everywhere), amano shrimp (hair algae specialists), otocinclus (diatoms + soft green), bristlenose plecos (community FW, 30g+), cherry shrimp (biofilm + leftover food). Saltwater: tangs, foxface, urchins, turbo snails, trochus. Nuclear option: 3-day blackout (cover tank, lights off, fish ok) clears most algae blooms.
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.
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