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.
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