How To Get Rid Of Brown Algae In My Saltwater Tank?

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How To Get Rid Of Brown Algae In My Saltwater Tank? Saltwater aquariums are a popular hobby, but with that popularity comes the potential for problems. One of those problems is brown algae growth.

Brown algae can rapidly take over a tank and cause a list of problems if your not careful. Fortunately, however, there are steps you can take to prevent brown algae growth and get your tank back to its healthy state.

So, in this blog post, we’ll discuss what causes brown algae in saltwater tanks and what you can do to get rid of it.

What is Brown Algae?

To start with, what is brown algae? Brown algae, also known as diatoms, is a type of algae that commonly appears in saltwater tanks. Diatoms are single-celled organisms called diatoms.

Diatoms get their brown color from the photosynthetic pigment, fucoxanthin. This pigment allows diatoms to absorb light from the blue and green spectrum, which is why they often appear brown in color.

They also eat organic fish waste like nitrates (N03) and phosphates (P04) which contribute to their growth. Brown algae also needs silica (SiO2) to survive which is a natural compound of silicon and oxygen.


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What Causes Brown Algae To Grow in A Saltwater Tank?

So what causes brown algae to grow in saltwater tanks? This is a question that many aquarists grapple with. While the answer is not always clear, there are several factors that can contribute to brown algae growth.

Brown algae can be a pesky problem in saltwater tanks, and it’s important to understand the causes so you can work out how to prevent it from becoming a problem.

To help you with this below we will take a look at some of the most common causes of brown algae in saltwater tanks. We will also discuss strategies for preventing and controlling brown algae growth.

Common Causes Of Brown Algae In A Saltwater Tank:

  • Silicates In The Water
  • Poor Light Quality
  • Presence Of Phosphates
  • Substandard Filtration
  • High Nitrate Levels

Silicates In The Water

This is the most common cause of brown algae in saltwater tanks. Silicates are a type of mineral that can be found in most types of aquarium sand and saltwater.

While silicates are necessary for the growth of diatoms, too much silicate in the water can lead to an overgrowth of brown algae.

To prevent this, it’s important to use high-quality aquarium sand and avoid using tap water in your tank. If you must use tap water, be sure to remove any chlorine or chloramines from it before adding it to your tank.

You can also invest in a good-quality reverse osmosis filter to remove silicates from your water before adding it to your tank.

Poor Lighting Quality

One of the most common causes of brown algae in a saltwater tank is poor lighting. Brown algae need light to grow, so if your aquarium isn’t getting enough light, it’s more likely to experience an algae bloom.

An algae bloom is basically an increase in the population of algae in an aquatic system. This can cause problems for the aquatic ecosystem, as the algae can block light from reaching other plants and organisms, and can also consume large amounts of oxygen.

Presence of phosphates

The presence of phosphate cans also encourages diatom growth. Phosphates are found in many aquarium products like fish food, gravel, and even some tap water. If your tank has high phosphate levels, it’s more likely that diatoms will start to grow.

This can also happen when you overfeed your fish, the uneaten food sinks to the bottom of the tank and rots. This rotting food release ammonia and other toxins into the water.

Substandard Filtration

Substandard Filtration can also play a part in diatom growth. If your filter isn’t able to remove all the waste and debris from your water, it can lead to an increase in diatoms (brown algae).

high nitrate levels

Last but not least, high nitrate levels can also cause of brown algae growth is high nitrate levels. Nitrates are a type of nutrient that algae need to grow. If your tank has high nitrate levels, it’s more likely that brown algae will start to grow.

Poor water circulation is another cause that can also cause diatoms to grow in your tank. Diatoms need good water circulation to thrive. If your tank doesn’t have enough water circulation, diatoms will start to grow.

Can Brown Algae Be Harmful To Your Fish?

While they are not typically harmful to fish, they can compete with other aquatic plants for resources and can cause the water to become cloudy.

If the brown algae population becomes too high, it can lead to a decrease in oxygen levels and an increase in ammonia levels, which can lead to your fish becoming stressed and eventually dying.

Another problem with brown algae is that it covers coral in no time at all. This causes the coral to suffocate and eventually die.

Therefore, it is important to monitor the growth of brown algae in your aquarium and take steps to control it if necessary.

How to get rid of brown algae in a saltwater tank?

So we’ve talked about what causes brown algae and how much of a nuisance they can be if it happens to you. Fortunately, however, there are several steps you can take to get rid of brown algae and restore balance to your saltwater tank.

1. Manually Remove Algae

When it comes to removing brown algae from your tank by hand, there are a few different options. You can use an algae scraper, a toothbrush, or even your fingers.

Each option has its own pros and cons, so you’ll need to decide which is the best for you.

Scrapers can be tough on your hands and can damage the tank if used improperly, while toothbrushes can be less effective and more time-consuming.

Fingers are easy to use and very effective, but they can also be messy. Ultimately, the best way to remove brown algae from your tank manually is to find the method that works best for you.

2. Algae Eating Animals

One of the best ways to remove brown algae from your tank is to use algae-eating fish. There are a variety of different types of fish that eat algae, so you’ll need to find the one that’s best for your saltwater tank

Algae-eating fish are great because they help to keep the algae population under control and they don’t require any special care or attention.

You can also use snails, shrimp, and other invertebrates to help control the algae population in your tank. Margarita snails are a popular snail for newbies to marine tanks and they love eating algae.

3. Increase Lighting

Brown algae thrive in tanks with low light levels, so increasing the light intensity can help get rid of it. Try using a higher wattage bulb or adding an additional light source to your tank.

If you suspect that poor lighting is the cause of the brown algae growing, try increasing the light levels and how long you use them to 6 to 8 hours.

This may mean getting a new light fixture or changing the bulbs in your existing fixture.

4. Use Chemical Treatments

Finally, Using chemicals is another way to remove brown algae in your saltwater tank. Chemical treatments work by killing the algae cells, causing them to break down and be removed by the filter.

Some of the most popular chemicals for treating algae are copper sulfate and potassium permanganate.

Important: When using these chemicals in your saltwater tank, it’s very important you follow the manufacturer’s instructions carefully to avoid harming your fish!

Tips To Prevent Further Outbreaks

When it comes to keeping your tank healthy, there are lots of easy tips you should follow. Many of these have been tried and tested by other fishkeepers which means they are a good guide to dealing with brown algae in the saltwater tanks.

Ways To Prevent Further Outbreaks:

  • Keep Up Regular Maintenance
  • Increasing UV Filtration
  • Check Nitrate Levels
  • Check Phosphate Levels

Keep Up Regular Maintenance

Regular maintenance is essential when you want to have a healthy aquarium. Remember to carry out regular water tests, gravel cleaning, and water changes. Excess waste is the main problem behind brown algae.

Regularly changing the water removes waste that encourages the growth of diatoms.

Brown algae normally appear on the glass at first. Removing it from the glass should hopefully prevent the algae from spreading to other areas of the tank.

However, when you are checking your tank, remember to check other areas as well.

Increasing UV Filtration

You can get rid of brown algae by increasing the amount of UV filtration in the tank. There are fantastic UV filtration systems available. It is a great idea to invest in a good quality one right from the start.

UV filtration helps when it comes to controlling access algae growth. Another advantage of UV filtration is that it removes waste from the water.

As mentioned, excess waste is one of the problems behind brown algae. Waste products produce nitrates which in turn feed the diatoms.

Check Nitrate Levels

One of the most important things you can do is to check the nitrate level. You have probably already bought a water testing kit, but make sure that you have a spare one.

Nitrates are produced in all aquariums and environments. Waste materials in nature give off ammonia which is broken down by a bacteria called Nitrosomonas.

As it breaks down, nitrites are formed. Other bacteria that goes by the name of Nitrobacter turn nitrites into nitrates.

The best way to manage nitrate levels is by checking them often. When you notice a problem, you need to ask yourself what is going on.

It is a matter of achieving the right balance of fish stock, cleaning crew, and systems such as filtration that help to keep your fish tank healthy.

Check Phosphate Levels

Does phosphate promote algae growth? Yes, it does. This process of breaking down phosphate takes place in your tank as well as in nature.

In nature, phosphates are mainly introduced to the ecosystem by food waste including animal foods. It is added to animal feeds as a preservative.

Unfortunately, unless you feed your fish a completely natural and organic diet, it is introduced to your tank in fish food.

As it starts to break down, it encourages algae growth. You may even have heard of algae blooms in the sea or freshwater. They occur mainly as a result of too much phosphate in the water.

When you want to prevent too much phosphate in your tank, monitoring the amount of food you feed your fish is essential.

Can you buy phosphate-free fish food? Yes, you can include krill and live Chaetomorpha algae. You may pay a little bit more, but it is worth it in the long run.


Yes, you can control brown algae in your tank. Can you prevent and eliminate it altogether? As it occurs naturally in nature, it is unlikely that brown algae in saltwater tanks are preventable altogether.

The best thing you can do is to monitor the levels of nitrate and phosphate. Stay on top of those and you have more or less won the battle. Think about your saltwater tank as an ecosystem.

Once you have got the balance right, you can look forward to many years of marine fish keeping and exploring new exciting fish that you can keep in your tank.

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