Reef aquariums come with baggage, just like any relationship. It is your responsibility as a hobbyist to understand and overcome the "not so fun" aspects of the hobby. What am I talking about here? Well, things like water changes, daily dosing, nuisance algae control and maintenance in general can steer even the most dedicated hobbyist away from a reef tank.

Among these tasks, nuisance algae control is probably the most frustrating for any level hobbyist. With such a wide range of pesky organisms and algae in your aquarium, sometimes it is difficult to keep up. In this article, we are going to attack one of the more problematic organisms that can occur in aquariums called Dinoflagellates, more commonly known as brown slime.

Dinoflagellates vary drastically and exist throughout the world in all aquatic ecosystems. They have a diverse set of niches and roles, often times having a big impact on the surrounding environment. They can be symbiotic with other animals (Zooxanthellae) or create a substantial threat (Red Tide). They are classified as Protists and have some similarities with other nuisance algae and organisms found in reef aquariums.

Most Dinoflagellates, including the type likely found in your aquarium, are both photosynthetic and capable of consuming prey (Mixotrophic). They can release toxins into your aquarium or into animals that may be consuming them with substantial ill-effects. Snails can die off and you might notice your fish losing appetite or become lethargic.

Dinoflagellates will form a colony consisting of many tiny individuals that appear like a brown slime on your aquascape, very similar to red slime, but they appear brown/ golden in color. The slime will trap small air bubbles as oxygen is produced via photosynthesis. They can also appear very similar to diatoms and will be difficult to identify properly for this reason.

Luckily, the similarities with other pesky nuisance algae and organisms help us hobbyists to prevent and eradicate Dinoflagellates using the same methods.

  1. Reducing nitrates and eliminating available phosphates is going to be your first step. This will impede the growth and reproduction of the organism, essentially starving it.
  2. Physical removal via siphon and cleaning will help reduce populations and with persistence, ideally eradicate them.
  3. Reducing your photoperiod to a minimum of 4 hours per day will limit the growth of Dinoflagellates. You can even utilize the "Black Out" method by completely turning off your aquarium lights for 72 hours.
  4. Using carbonscavenger resins or even ozone will remove toxins released into your aquarium water once Dinos become a problem. This will help prevent your herbivorous grazers from falling victim to these toxins.

If the Dinoflagellates become out of control and none of the above methods seem to help, you do have one last resort. Raising pH has been reported by many hobbyists to make quick work of problematic Dinos. The idea behind this method is that raising the pH will limit the carbon dioxide available for photosynthesis ultimately killing the Dinoflagellates. This can have dramatic effects and quickly kill off large populations of Dinoflagellates, especially if pH is raised to levels above 8.5.

Raising pH can safely be done with the use of additives such as kalkwassertwo-part solutions and/or buffers. Of course, you do not want to make quick or large pH changes as this will lead to stress on your corals and fish. Ensure you maintain stability in your aquarium by keeping the appropriate levels of calcium, alkalinity and magnesium through the process.

Keep in mind that it is possible for the Dinoflagellates to return once pH is maintained back at normal levels. Furthermore, this method is hit-or-miss since proper identification of Dinoflagellates is difficult. The known effects of limiting carbon dioxide may quickly kill one species of Dinoflagellate but have little effect on another.

We can see a consistent theme in preventing nuisance algae and organisms in your aquarium. Arming yourself with knowledge and staying consistent is your best defense against this "baggage" that comes with keeping a reef aquarium.