If you’ve been a reef hobbyist long enough, chances are you’ve encountered dinoflagellates, or "dinos." These persistent pests are notorious for invading reef tanks, creeping onto your sandbed, rocks, and even your corals. The worst part? They can vanish overnight, only to reappear when the lights come back on, leaving you feeling helpless and frustrated. But don’t panic—dinoflagellates, while tricky, are not undefeatable. In this post, we’ll walk you through the steps to identify, tackle, and ultimately rid your tank of these troublesome invaders. It’s time to take back control and get your reef back on track!
What Exactly Are Dinoflagellates?
Dinoflagellates are single-celled organisms that can rapidly proliferate in saltwater aquariums, often looking like bubbly, snot-like clumps. Unlike red slime algae (cyanobacteria), which are slimy and red, dinoflagellates have a more distinct, slimy appearance and tend to thrive on substrates like sandbeds, live rock, or even corals themselves. The problem? These microscopic pests not only make your tank unsightly but also compete with your corals for precious space and resources.
One of the most frustrating characteristics of dinoflagellates is their mysterious cycle—they often disappear at night and reappear when the lights turn on. This can make it challenging to pinpoint and treat the problem effectively, but with the right approach, you can win the battle.
Step 1: Identify the Root Cause of the Problem
Before diving headfirst into treatment, it’s important to understand why dinoflagellates are thriving in your tank. A key factor is often low nutrient levels. If both nitrates and phosphates in your tank are testing at zero, you're likely providing the perfect conditions for dinoflagellates to take over. In a nutrient-deprived environment, these pests can easily outcompete other beneficial organisms, including the ones that help keep your tank in balance.
When nutrients are too low, you’re essentially setting the stage for dinoflagellates to flourish. Fortunately, there’s a clear fix—getting your nutrient levels back on track.
Step 2: Boost Nutrient Levels
The first and most straightforward solution is to increase your nutrient levels. To do this:
- Feed your fish more to increase organic matter in the water.
- Dose nitrates and phosphates
These products will raise your nutrient levels, helping to disrupt the imbalance that allows dinoflagellates to thrive.
Step 3: Bring in the Beneficial Bacteria
Once your nutrient levels are on track, it’s time to introduce beneficial bacteria to outcompete the dinoflagellates. These bacteria work by taking up space and nutrients, starving the dinoflagellates of what they need to survive. These bacteria aren’t a magic cure-all, but they can help tip the balance in your favor by competing with the dinoflagellates for resources. It’s one more tool in your arsenal to restore harmony to your tank.
Step 4: Physically Remove the Dinoflagellates
While bacteria can help reduce the dinoflagellate population, you can’t rely on them alone. To really make a dent in the problem, you’ll need to physically remove the dinoflagellates.
Use a siphon to manually remove them from the sandbed or rocks. Doing this regularly—ideally daily—will help you keep their numbers in check. If you see the dinoflagellates floating in the water column, you can use filter socks or fine mechanical filtration to capture and remove them as they break apart.
Step 5: UV Sterilizers – Your Secret Weapon
A UV sterilizer is a highly effective tool for targeting the free-floating dinoflagellates that escape from the sandbed and rocks. UV sterilizers work by zapping these organisms as they float in the water column, but keep in mind—they won’t help with dinoflagellates that are attached to surfaces.
For optimal results, use a Pentair UV sterilizer (we recommend the 25-watt model for tanks up to 130 gallons). The flow rate through the sterilizer should be adjusted to target protozoa and bacteria, ensuring it effectively addresses the types of dinoflagellates that can be eradicated using UV.
Step 6: Total Darkness – The Power of a Blackout
Dinoflagellates are photosynthetic, meaning they depend on light to grow and reproduce. One of the most powerful tactics to fight them is a complete blackout. By covering your tank with opaque sheets or black cardboard, you block out light entirely for 3-4 days.
While this may seem drastic, it’s highly effective. During the blackout, your bacteria will have a chance to outcompete the dinoflagellates, and without light, the dinoflagellates will struggle to grow. When you uncover the tank, you should notice a significant decrease in their presence.
Patience and Persistence – The Key to Victory
While these steps can work wonders, dealing with dinoflagellates is not a quick fix. It may take weeks—possibly even months—to fully eradicate them from your tank. But by sticking to these proven steps and remaining patient, you’ll eventually see your efforts pay off.
Remember, patience is key in the fight against these microscopic invaders, and with persistence, your tank will be back to its beautiful, thriving self in no time.
Dinoflagellates can be a tricky problem, but with the right approach, they are definitely manageable. By boosting nutrients, introducing beneficial bacteria, physically removing the pests, and using UV sterilizers and darkness, you can outsmart these persistent invaders. Stay patient, monitor your progress, and your reef will be flourishing once again!
