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Are red algae harmful for saltwater fishes in marine aquarium?

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Unicellular red algae do photosynthesis and add oxygen to the aquarium so this is beneficial for aquarium and fishes are comfortable staying with it because it creates a healthy marine environment. But red algae are harmful to plants while it blooms because it needs the same nutrients to grow which aquatic plants need and it releases exotoxins which can kill fishes.

So if you see overall, then you may understand that red algae is not so bad what you think but you need to prevent the red algal bloom because that is harmful.

Now you should know

Why does red algal bloom occur in a saltwater aquarium?

Like any other type of algae, red algal bloom occurs just for some reasons which you should know if you are keeping a saltwater aquarium

  • Nutrient imbalance

Nutrient imbalance is one of the main causes of red algal bloom that happens in a saltwater aquarium. Nutrient imbalance happens just for lack of maintenance. Excessive foods and the waste of fishes increase the nutrient level in the water column and after a while algae start to bloom in the aquarium. Red algae bloom due to high nitrogen and phosphorus levels in the water. So try to clean water if you want red algal bloom in your aquarium.

  • Lack of water flow

Your saltwater aquarium may not get the same water flow at every corner of it. So this can be a serious cause to bloom red algae. So you need to check if you have a marine tank set up. You need air stones, a good air pump which can flow water at every corner of the tank.

If the water flow stops anywhere then a dead stop may create at that particular spot which is a very suitable place for algae growth. So try to remove dead spots by good water flow.

  • Excessive lights

Lights are good to grow aquatic plants and algae. But if you provide excessive lights then algae will grow faster than plants and all of the nutrients in the aquarium will be taken by algae. At that point, plants will start dying gradually. So don’t keep your aquarium under the sunlight directly and turn on the lights not more than 6 hours a day which is good for a marine fish tank.

These are the main three causes why red algae bloom in your saltwater aquarium. Try to maintain these to prevent algae bloom but if you are facing this problem now then you have to apply different strategies to get rid of this problem.

Read more:- What would happen if freshwater fish is placed in saltwater?

How to remove red algae from the saltwater aquarium?

Removal of red algae is an easy thing till a certain time but when it blooms then, it quite impossible to remove fully. But there are some ways to fight against it. Let’s discuss these ways

Basic solution

1st of all you have to change 20% of whole water before doing anything and then check the light source. If you don’t reduce the time duration of turning on the lights then you can’t check the algae growth in your saltwater aquarium.

So first and foremost thing you must do is put a cover on the aquarium and prevent lights to enter it. This process should go for 3-4 days. Fishes can easily stay in these days without ready-made food. It can take algae and other microorganisms as food during these days and fishes don’t bother dark environments so without light it’s not a problem for fishes.

After 3-4 days you have to change the water again. Minimum 10-15% of whole water should change and then you should add CO2 dosage according to your tank condition. If you have a good CO2 concentration then you don’t need to add it. You should apply this whole process minimum of 2-3 times.

If you are worried about other types of algae then you must read my article where I’ve discussed fully how to remove algae from an aquarium

Read more:- How Many Algae Eaters For Fish Tank: 5, 20, 55, 60g & More

Chemical solution

If you don’t see any progress by doing this then you have got some serious trouble. Now you need some chemicals to remove red algae from your saltwater fish tank. Here I can suggest some good products which you can use to get rid of this problem.

The number one product is Chemi Clean aquarium treatment. This is probably the best product, which can help you to get rid of this red algae problem. Not only red algae, you can use this product for blue-green algae also. Basically, this removes harmful strains from algae and that’s why algae can’t release toxins after gradually it dies.  This removes Cyanobacteria well.

So to use this chemi clean you need to know about its dosage and its usage. Try to provide one drop per one gallon of water. After mixing it with aquarium water let’s leave your aquarium putting it undercover. Don’t worry about fish. These will stay fine. This dosage will take a maximum of 30-45 hours to remove 75% of red slime. After that change 40% of whole water and this is mandatory.

After changing water 2nd dosage you should provide. Let’s provide 2nd dosage and keep your aquarium undercover again for the next 40 hours. After 40 hours you need to change another 40% of the water of the aquarium. After this two-step, red algae will remove.

But you should apply this method for the next few months to remove it forever from your saltwater aquarium. Once a month is enough to apply this method to remove red slime. But make sure to turn off the protein skimmer and UV sterilizer while running this method. Keep a good air stone to oxygenate the tank at this time.

Do you want to know are other types of algae harmful or not for your aquarium? Then go here 

Read more:- How to build saltwater aquarium from scratch

Final thoughts

Red slime is beneficial for the saltwater aquarium but if you see that that is going to out of control then you should go for the common and basic solution which I’ve discussed. Now if you are suffering from red algae bloom for several months then you should go for a chemical treatment to solve this issue.

But don’t worry; this can be removed if you apply these methods well. So try to copy this and restart your hobby from today.

So best of luck & happy fishkeeping 🐟

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