Aquarium plants die for predictable reasons — diagnose by elimination. 1. Insufficient light. Low-light plants (anubias, java fern, crypts) need 30-40 PAR. Stem plants need 50-100 PAR. Carpets need 80+ PAR. A single LED strip in a 75-gallon often fails. 2. Missing CO2. Stem plants + carpets fail without pressurized CO2 or daily liquid carbon (Excel/Easy-Carbo). Don't add carpets to a low-tech tank. 3. Temperature. Most plants want 72-78°F. Discus tanks (84°F+) struggle with most plants. 4. Nutrient deficiency. New tanks lack potassium + iron. Yellowing leaves = K or Mg shortage. Pinholes = K. Dose Easy Green (Aquarium Co-op) or EI fertilizers weekly. 5. Emersed-to-submersed melt. Most aquarium plants are sold grown emersed (out of water). When submerged, old leaves melt off + new submerged-form leaves grow. This is NORMAL for crypts, vallisneria, swords. Wait 4-6 weeks before judging. 6. Algae overgrowth. Hair algae or BBA on leaves blocks light. Treat algae or rehome plants. 7. Substrate. Root feeders (swords, vallisneria, crypts) need root tabs every 3 months in inert substrate.
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.
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