🦠 Dinoflagellates (Dinos)

Dinoflagellates, commonly called "dinos," are single-celled organisms that can quickly take over a reef tank, smothering corals and creating an unsightly brown or golden film. They are one of the most frustrating pests in the hobby because they are difficult to identify correctly and even harder to eliminate.

📋 Quick Facts

🔍 Identification

Dinoflagellates are often confused with other nuisance algae like diatoms or cyanobacteria. Key identifying features:

• Stringy appearance - Produces long, snotty strings when disturbed
• Bubbles - Creates oxygen bubbles trapped in a mucus matrix
• Returns quickly - Comes back within hours after being blown off
• Covers everything - Spreads over sand, rocks, coral, and glass
• Daily cycle - Often worse in afternoon, recedes at night
• Microscope confirmation - Shows characteristic spinning cells

Dinos vs. Similar Pests

⚠️ Common Causes

• Ultra-low nutrients - Nitrates and phosphates near zero create ideal conditions
• New tank syndrome - Immature bacterial populations can't compete
• Antibiotic use - Kills beneficial bacteria, allowing dinos to thrive
• UV sterilizer overuse - Eliminates competing organisms
• Excessive cleaning - Removes beneficial biofilm and bacteria
• Silicates in source water - Some dino species thrive on silicates

💊 Treatment Options

1. Raise Nutrients (Most Important)

Counterintuitively, the best approach is often to increase nutrients:

• Target nitrates: 5-10 ppm
• Target phosphates: 0.03-0.1 ppm
• Reduce or stop GFO/carbon dosing
• Feed more heavily
• Dose potassium nitrate (KNO3) if needed

2. Increase Biodiversity

• Add live phytoplankton regularly
• Dose beneficial bacteria (e.g., Microbacter7, PodMix)
• Add copepods and amphipods
• Consider a refugium with chaeto
• Add "dirty" live rock from an established tank

3. Blackout Method

• Complete darkness for 72 hours
• Cover tank completely (no light leaks)
• Turn off refugium light
• Keep flow and filtration running
• Monitor temperature
• Warning: May stress corals; best combined with other methods

4. UV Sterilization

• Properly sized UV sterilizer with slow flow rate
• Kills free-floating dinos in water column
• Won't eliminate dinos on surfaces
• Best used in combination with other treatments

5. Manual Removal

• Siphon out during water changes
• Turkey baster to blow off rocks (then filter/skim)
• Replace fine filter floss frequently
• Run skimmer wet

6. Chemical Treatments (Last Resort)

• DinoX - Commercial dino treatment
• Hydrogen peroxide - Spot treatment (risky)
• Vibrant - Bacterial competition product
• Warning: Chemical treatments can harm corals and crash tanks

🐟 Biological Controls

Some animals will eat dinoflagellates, but they're rarely a complete solution:

• Sea slugs - Some species graze on dinos
• Cerith snails - Will eat some varieties
• Nassarius snails - Disturb sandbed, limiting growth
• Sand-sifting gobies - Keep sand stirred

⏱️ Treatment Timeline

🛡️ Prevention

• Don't chase "zero" nutrients - some is healthy
• Maintain diverse bacterial populations
• Don't overuse UV sterilizers or antibiotics
• Cycle tanks properly with biodiversity in mind
• Avoid overly sterile setups
• Use quality RODI water to limit silicates

❌ Common Mistakes

• Treating dinos like regular algae (more cleaning makes it worse)
• Continuing to run GFO during outbreak
• Giving up too soon - treatment takes weeks to months
• Not confirming identification (many misdiagnose diatoms as dinos)
• Using antibiotics which kill competing bacteria

📚 Summary

Dinoflagellates are challenging but beatable. The key is understanding that they thrive in ultra-clean, low-nutrient environments with poor biodiversity. By raising nutrients, adding beneficial organisms, and being patient, most tanks recover within 1-3 months. Avoid the temptation to "clean more" - this only makes dinos worse.