Dinoflagellates ("dinos") are single-celled algae that bloom in nutrient-stripped reef tanks (ULNS conditions). They form snotty brown strings on rockwork + sand and produce bubbles. Toxic to coral and fish.
Ultra-low-nutrient systems where competing algae cannot grow. Common after switching from high-nutrient to low-nutrient (heavy GFO, biopellets).
Multiple effective treatments exist. Pick based on your tank type, livestock sensitivity, and severity. Always treat in a separate quarantine/hospital tank - most medications are toxic to coral, invertebrates, and live rock biology.
Maintain modest nutrient levels (NO3 5-10 ppm, PO4 0.03-0.05 ppm). Don't over-strip with GFO/biopellets.
Brown stringy mucus on rockwork or sand. Bubbles trapped in the strings. Strings detach with current and float.
Ultra-low-nutrient systems where competing algae cannot grow. Common after switching from high-nutrient to low-nutrient (heavy GFO, biopellets).
Raise nitrate/phosphate: Reduce GFO + biopellets. Increase feeding. Target 5-10 ppm nitrate, 0.03-0.05 ppm phosphate. Dinos die when other algae can compete.
Maintain modest nutrient levels (NO3 5-10 ppm, PO4 0.03-0.05 ppm). Don't over-strip with GFO/biopellets.
High - can cause coral and CUC die-off
Always treat in a separate quarantine or hospital tank. Most medications are toxic to coral, invertebrates, and live rock biology.
Browse the full disease database for 45 aquarium conditions with treatment protocols, or check the care library for prevention-focused husbandry guides. Use our symptom matcher to rank likely diseases from observed signs, the water parameter checker to diagnose related water-quality issues, or the QT timeline calculator to plan a treatment schedule.