LED choice depends on tank type + plant/coral demands + budget. Fish-only freshwater: any inexpensive 6500K LED with 0.5-1 watt per gallon. NICREW Classic LED Plus, Aqueon LED, Finnex StingRay (mid). $30-80. Low-tech planted (anubias, java fern, crypts): 30-40 PAR at substrate. Finnex Stingray, NICREW SkyLED Plus, Hygger 24/7 Plant. 6-8h photoperiod. $40-100. Medium-tech planted (rotala, ludwigia, alternanthera, bacopa): 50-80 PAR. Fluval Plant 3.0, NICREW HyperReef, Twinstar 600S/900S. CO2 + Excel optional. $100-250. High-tech planted (carpets, reds, demanding stems): 80-120+ PAR. Twinstar 600E/900E, Chihiros WRGB II + WRGB II Pro, ONF Flat One+, Aquasky 2.0 G7, Aquatic Life Hybrid T5+LED. Pressurized CO2 mandatory. $250-500. Softie + LPS reef: 100-200 PAR. Reefbreeders Photon V2, ABI Tuna Blue/Sun (DIY), AI Prime 16HD, Kessil A360X. $200-450 per fixture. SPS reef: 250-450 PAR. AI Hydra 32HD/64HD, EcoTech Radion XR15/XR30 G6, Reefi Uno, Maxspect Razor R420. $400-1,200 per fixture. Buying checklist: programmable timer + sunrise/sunset ramp, IP65 waterproof rating, dimmable, 5+ year warranty.
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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