Dinoflagellates: Causes of Appearance and Control Methods

Introduction

This material addresses the causes of dinoflagellate outbreaks in marine aquariums and effective methods to combat them. Despite the common belief that dinoflagellate occurrences are unpredictable, there are scientifically based approaches to solving this problem.

Three Main Biological Processes of Water Filtration from Nutrients

In a marine aquarium, three variants of biological water purification processes are possible:

Natural biofiltration process – this is the optimal and most effective way to maintain water clarity and ecosystem balance. It includes two key stages of the nitrogen cycle:

• Nitrification – conversion of ammonia to nitrite, and then to nitrate with the help of bacteria.
• Denitrification – consumption of nitrate by bacteria with the participation of phosphates.

Thanks to this process, the balance of microorganisms is maintained, water remains clear, and corals and fish develop in a healthy environment.

These processes are primary and we should restore them as soon as possible, as their interruption is one of the main causes of dinoflagellate appearance in aquariums.

Phytoplankton filtration (phytoplankton outbreak and greening of all water in the aquarium) - intermediate in effectiveness. Phytoplankton consumes nutrients and microelements, suppressing other filtration variants. This option is not suitable for keeping a reef aquarium for obvious reasons.

Dinoflagellate filtration - the least stable form, disrupting normal functioning of the aquarium ecosystem and causing death of most corals within a few months. Dinoflagellates consume most microelements and phosphates very quickly until they are completely depleted, regardless of the ballasts for their consumption as in the example of the nitrogen cycle.

Biological Balance in a Healthy System

In a balanced system with proper biological filtration, dinoflagellates do not develop. When they enter a healthy system, they are quickly neutralized by natural biological processes. Similarly happens with phytoplankton - in a healthy system, it is consumed by microorganisms and corals, not causing a "water bloom" outbreak.

Key Factors in Dinoflagellate Development

Silicate (Silicon) as the Main Trigger and Excess of Other Microelements Participating in Biofilter and Coral Nutrition Processes

The main factor causing dinoflagellate outbreaks is elevated silicate (silicon) content in water. Dinoflagellates can develop even at normal nitrate and phosphate levels if silicate concentration is high.

Critical silicate values:

• At levels around 350 units, an outbreak may begin
• Normal silicate content should be around 100-200 units
• During dinoflagellate outbreaks, values around 1000 units and higher are typically observed

Sources of silicate:

1. Ceramic and Plastic materials - low-quality ceramics in the aquarium can release significant amounts of silicate (silicon), and the same applies to products made from plastics suitable for marine aquariums.
2. Low-quality salts - many aquarium salts contain excess silicate.
3. Reverse osmosis system - faulty or insufficiently effective RO systems can allow silicate to pass through, which accumulates in your aquarium.

Diagnosing Elevated Silicate Levels

A visual indicator of high silicate content is the appearance of a reddish coating on aquarium glass. Home tests for silicate are often inaccurate, so it's also recommended to focus on external signs.

Another important indicator is pH change:

• With normal biology, pH is stably high
• Rapid increase in ORP and decrease in pH with constant carbonate hardness indicates disruption of biological processes
• Persistent decrease in pH often precedes dinoflagellate outbreaks as a symptom

Testing Ceramic Materials

Before using ceramics in an aquarium, it's necessary to:

• Soak it in a separate container with water for 7-10 days
• Test the water for silicate content
• Not use materials that release significant amounts of silicate
• Prefer live rocks with already established microflora

Consequences of Dinoflagellate Outbreaks

When dinoflagellates dominate the system, the following changes are observed:

1. Decreased pH - a persistent drop in pH level that is not corrected by standard methods.
2. Disruption of biological balance - suppression of normal microflora in the presence of high ORP due to the filtering action of dinoflagellates consuming all nutrients from the water.
3. Inhibition of coral growth - decreased polyp activity, loss of coloration, gradual death due to starvation and harmful, irritating effects from the dinoflagellates themselves on corals.
4. Formation of a vicious cycle - dying organisms create additional nutrition for dinoflagellates.

Methodology for Combating Dinoflagellates

1. Elimination of Silicate Sources

• Check and replace ceramic materials
• Remove all unnecessary plastic materials such as cellular PVC grids for corals, etc.
• Control water quality after the reverse osmosis system
• Test salt for silicate content
• Minimize water changes during an outbreak
• Reduce White and Red channels of the light fixture to minimum for 3-4 weeks

2. Removal of Dinoflagellate Biomass

• Mechanical collection of dinoflagellate biomass
• Use of filter bags to prevent their spread
• Regular removal of visible accumulations

3. Restoration of Normal Biofiltration

• Maintain stable nitrate-10 and phosphate-0.1 levels
• Regular dosing of carbon (e.g., glycerin at a rate of 0.5 ml per 200 L)
• Maintain normal fish feeding regime to support the Nitrogen Cycle
• Provide minimal amounts of microelements; don't dose more as you will be feeding dinoflagellates with these microelements, provoking their growth

4. Stabilization of Nitrification and Denitrification Processes

• Nitrification: conversion of ammonia to nitrate
• Denitrification: conversion of nitrate to gaseous nitrogen
• Maintain optimal nitrate to phosphate ratio (approximately 1:0.14)
• Control sufficient phosphate input for denitrification

5. Prevention of Parametric Fluctuations

• Prevent complete disappearance of phosphate from the system
• Avoid abrupt changes in feeding regime
• Systematic control of water parameters
• Immediate removal of dead organisms to prevent secondary outbreaks

6. Proper System Feeding

• Do not use the "starvation" method - this disrupts biological cycles and exacerbates the problem
• If a mild bacterial outbreak occurs (water cloudiness), stop carbon dosing for a few days, but do not stop feeding the fish
• Use fish foods rich in phosphate (spirulina, nori) to maintain the necessary phosphate level for maintaining the denitrification process, or simply dose Chemical Phosphate using a doser to stabilize phosphate in the water
• Feed fish regularly to avoid fluctuations in the biological processes of the Nitrogen Cycle and Denitrification

Conclusion

Effective control of dinoflagellates requires a comprehensive approach aimed at eliminating the main trigger (silicate) and restoring normal biological processes. It is critically important not to allow system starvation and to maintain stable water parameters. By following these recommendations, the dinoflagellate problem can be successfully resolved.