Are you worried about cyanobacteria growing underwater in your reef tank? The small, slimy, and stringy substance in the live rock called cyanobacteria can invade the tank and make it dirty. Though it is not very easy to deal with it with one single method, it is not very difficult to get rid of them if you combine multiple ways.
To get rid of cyanobacteria in reef tanks, you should consider changing the water frequently, keeping phosphate and nitrate level in check, maintaining proper water circulation, replacing the old bulbs, using RO/DI water, and other methods.
In this article, I am going to share the main causes of cyanobacteria bloom in the reef tank and 10 effective ways to get rid of them along with debunking the myths regarding cyanobacteria.
Let’s dive in.
What is Cyanobacteria?
Well, before going to the main discussion, let’s know something about what cyanobacteria are. Do you think they are algae? If you think of them only as ordinary algae, that’s nothing more than an optical illusion.
Cyanobacteria is a photosynthetic little organism. It is called red slime algae by some aquarists though it comes with other colors such as deep purple, black and green. It is a type of bacteria where the properties of algae are also present.
Being one of the oldest organisms, cyano or red slime algae was present even before 3.5 billion years from now. As they are microscopic, you can not see a single cyano with naked eyes. You can see them when they are clustered together and make a colony of their own.
Though cyanobacteria in reef tanks are not very toxic, in the ocean there are some toxic red species. In our reef tanks, cyanobacteria can cause some bad side effects. Apart from being ugly, they compete with the corals to grow faster. They grow rapidly and can block the light and even photosynthesis by covering a vast surface.
Additional Read: How To Get Rid of Algae in A Reef Tank
Main Causes of Cyanobacteria Blooms
Now that you know something about cyano, let’s move to the main discussion. There can be dozens of reasons why cyano blooms occur in reef tank water. One of the main reasons is the imbalanced and too high nutrient concentrations in the water.
You can compare the cyano bloom process with your body. If you consume a lot of carbohydrates like rice and sugar, your waistline will bloom day by day.
It is the same for the reef tank. When the phosphate and nitrate level or other organic compounds go high in the reef tank, the cyano blooms occur. Here are some of the causes that help to form the excessive nutrients in the water and thus causes cyano bloom:
Insufficient Air Bubbles/Protein Skimmer Not Working Efficiently
A protein skimmer has to create and fill the tank water with tiny air bubbles. When the protein skimmer does not output the best efficiency or you do not have the suitable protein skimmer to cover the tank, the air bubbles created by the skimmer might be insufficient. And this insufficiency of air bubbles can trigger the cyano to thrive.
Low Water Circulation
If the water flow or movement in certain points of the tank is slow, that can be one of the main causes of red slime algae to grow. When the slow water movement is accompanied by the excess amount of dissolved nutrients, cyano blooms occur more rapidly.
Infrequent Water Changes
If you do not change the water at least once a week, it might cause the red slime algae, especially the red ones. Regular water changes keep the water clean and free from cyanobacteria by diluting the nutrients.
Adding Premature Live Rocks
If you have added live rocks that have not reached their maturity yet, they work as a breeding ground for the cyanobacteria.
Using Tap Water
Using water straight from the tap or any bad water source can invite the cyanobacteria. It is because water from those sources come with a higher level of phosphate and nitrate.
Supply of Excess Food
If you supply your reef tank with excess food, that will skyrocket the nutrients level. Overfeeding does not help marine animals to grow quicker. It is rather the phosphate and nitrate level that go up and they inspire cyano growth.
Myths and Realities about Cyanobacteria
You might have heard that cyano can kill you or it is light that causes the cyano bloom. These are not completely true and thus can be categorized as a myth.
Keep in mind that cyano bloom that takes place in the tank is not deadly in most cases. The exotic blooms that grow in the wild might have toxic elements in them.
On the other hand, many believe that light is the ultimate cause of the cyano bloom. Again, this is not true. Though light can contribute to the growth of red slime, it is not the ultimate cause or key element.
Just like two myths we have just mentioned, here are three more myths and realities that have spread like wildfires in the reef tank community:
Myth 1: Only Antibacterial products can kill cyanobacteria
Reality: Using antibacterial products is not the only way to kill cyanobacteria. There are a variety of other ‘safe’ ways to kill and prevent the red slimes. There is no doubt that using antibacterial products can kill cyanobacteria, but they are not safe for other marine creatures and the ecosystem. Using antibacterial products mercilessly in the tank to kill cyanobacteria will likely threaten the safety of everything else in the aquarium.
Myth 2: The more you apply nutrient additives, the better it is.
Reality: This is also not true. Through calcium, stony corals, or buffers for clams are important for the better growth of marine creatures, other commercial additives claiming to come with ‘secret ingredients’ are not so effective.
Keep in mind that additives only work to boost the dissolved organic compound concentrations and nothing else. Using too many additives is like inviting cyanobacteria in the dinner table. Avoid the marketing scam that might be tempting you to buy their additives with ‘secret and unique ingredients’.
Myth 3: Cyano blooms can be eliminated overnight.
Reality: I wish it were true! But, it is far from the truth. It is not possible to eliminate the cyano blooms by any magic. It takes time and patience to eliminate.
Determining the underlying cause of the cyano bloom is the most important step you should take to control the cyano bloom. The quicker you can trace the cause(s), the faster you can take action and bring the bloom in control.
On the other hand, though cyano bloom can go away with proper measures, it can also come back if the aquarium ecosystem is not controlled impeccably.
11 Effective Ways to Get Rid of Cyanobacteria in the Reef Tank
There are some effective ways you can use to prevent the cyanobacteria from destroying the ecosystem of your reef tank. Keep in mind that finding the causes of cyanobacteria in your reef tank is the best thing to start with to take effective measures.
Let’s now see 10 effective ways you can put to use if you are willing to say good-bye to the cyanobacteria from the reef tank:
Use RO/DI Water to Refill Your Reef Tank
If your water source is not pure, you are going to welcome algae instead of corals. You should always avoid using non-purified tap water. Because tap water comes with a variety of dissolved nutrients that increase phosphate and nitrate level.
Do you believe that adding only a dechlorinator substance to purify the tap water is adequate? We don’t think so. If you are willing to treat the present cyano bloom and prevent them from reappearing in the future, you must ensure that you use RO/DI water for your reef tank.
Keep the Nitrate Level in Control
Cyanobacteria thieves if the nitrate level in the water is out of control. So, always make sure that you have control over the nitrate level. It is best to keep the nitrate level within 10 ppm.
To lower the nitrate level, proper filter maintenance, following the accurate feeding techniques, and small-scale frequent changes of tank water are helpful.
Consider Changing the Tank Water More Frequently
How often do you change the reef tank water? Though you might get illusioned that you are doing it pretty frequently, it might not be enough frequency if you see cyano bloom thriving.
If you are not changing your water at least once a week, you are not on the right track. In case you do not have time for frequent changing of water, consider changing the water gradually.
Control the Phosphate Level
The high phosphate level creates a perfect atmosphere for the cyano bloom. The phosphate level in the reef tank should be 0.05 ppm or below. Reduce the phosphate level if you want to bring the order back in the tank and prevent the cyano from coming back.
However, one alarming thing is that red slime can have phosphate locked in it. That’s why you might not get a higher phosphate level in the water even though the cyano bloom is going on at the tank.
Yet, try to keep the phosphate level as low as possible so that it does not inspire the cyanobacteria to grow.
Clean the Cyano Residue
During changing the water of the tank, try to remove the cyano residue from the surface and the live rocks with a brush. Bring the red slime algae out of the tank with a siphon hose. Using a toothbrush at the end of the hose can accelerate the cleaning process.
Do Not Add Premature Rocks
Do not add premature rocks in your reef tank unless you want to make your tank a welcoming mat for the cyanobacteria. Choose only mature and suitable live rocks that help the fishes and corals and create a good water ecosystem.
Ensure Sufficient Air Bubbles
Make sure that the protein skimmer you have in the aquarium is working effectively to create adequate air bubbles in the tank. Find the best protein skimmers even if those might seem costly.
Replace the Old Bulbs
If you are using old light bulbs, there is a chance that they are contributing to the growth of the red slime algae. By the passage of the time, the light spectrum of bulb shifts.
Every light bulb comes with a recommended life span. When this period is expired, the light spectrums start to change. Though the bulb can still illuminate the surface, it inspires the growth of cyano and other algae inside the tank.
That’s why you should consider replacing the metal halide lights and T5 light bulbs regularly. May be it is time to bring home a good LED fixture for your reef tank.
Maintain Proper Water Circulation
If cyanobacteria bloom is occurring just at certain points of your tank, it is probably due to the lack of the water circulation at those points. Due to detritus build-up, cyanobacteria shine in the low flow areas where the water is not properly aerated.
To solve this problem, you can either rearrange the rocks in the aqua-space or add powerheads or wave makers so that the dead spots or low flow areas come under adequate water circulation.
Use Commercial Cyano Treatments
If the strategies mentioned above are not enough for your reef tank to remove the cyanobacteria completely from the water, you can use commercial cyano treatments.
While using anti-bacterial agents might be threatening for the fishes and other creatures in the tank, using any chemical cyano treatment marketed commercially can be a safer alternative.
11. Introduce Clean Up Crews To Remove Cyano
Natural clean up crews can help to fight with cyano bloom. Astrea Snails, Cerith Snails, Nerite Snails and Turbo Snails can help to some extent by eating cyano.
I hope that now you know all the ways about how to get rid of cyanobacteria in reef tanks. Trace the causes of the cyano bloom in your aquarium, apply the corrective methods one by one or together to see what works best for you. Using a chemical agent should be your last resort to seek.
Keep in mind that getting rid of cyanobacteria is a gradual process. You have to be active and patient to find the best results out of the ways I have mentioned above.