Saltwater Issues
Algae Outbreaks — Cyano, Dinos, Hair Algae
Symptoms
- Cyano: red, purple, or black slimy sheets, often with trapped air bubbles
- Dinoflagellates: brown, snotty strings with bubbles, worst after lights-on
- Hair algae: green tufts on rock, glass, and equipment
Likely causes
- Cyano — excess nutrients combined with low flow and old lights
- Dinos — nutrients stripped too low (nitrate near 0, phosphate near 0) starving algae and letting dinos take over
- Hair algae — leaching phosphates from new rock, overfeeding, or insufficient clean-up crew
Immediate steps to take
- Manually siphon out as much algae as possible during a water change
- Increase flow in dead spots where slime builds up
- For dinos specifically — RAISE nutrients: feed more, dose nitrate to 5 ppm and phosphate to 0.05 ppm
- For cyano and hair algae — REDUCE nutrients: skim harder, feed less, run GFO or carbon dosing carefully
Long-term prevention
- Aim for measurable nitrate (2–10 ppm) and phosphate (0.03–0.08 ppm) — not zero
- Replace reef lights every 12–18 months; old spectra favour nuisance algae
- Maintain a balanced clean-up crew: hermit crabs, turbo snails, urchins, tangs as appropriate
- Quarantine new rock and aquascape with cured, pest-free stone
Recommended products & practices
Identify before you treat — cyano, dinos, and hair algae each need opposite approaches. A dirty water cup under a microscope, or a clear photo, will save you weeks of guessing.