Brown Stringy Algae on Sand-Remove It Without Any Hassle

Want to know the causes of brown stringy algae on sand? Or, Are you searching for a solution to prevent brown algae growth?

If you are having a brown filamentous layer on your sand-like dust, you can surely consider that it is a diatom. Diatoms are mainly unicellular and brown to golden colored. They are mainly made of silica nitrates having a bony structure under the class Bacillariophyceae. They spread a golden film on the sand and destroy the look of the aquarium.

Due to the presence of enough food material, low light, and favorable conditions for their life, they bloom on the sand and regenerate which can be removed by following some special techniques like checking phosphate levels and other nutrients.

Go through the detailed information about these techniques and have the solution to your problem.

4 Causes of Brown Algae Grow on Sand

Brown Algae on Sand

To prevent brown algae growth on the sand, you need to know the causes of their development first. Let’s have an overall concept about them.

1. Presence of Silica

When silica remains on the sand, it continuously supplies the food for diatoms. On the other hand, the frustules or hard porous cells are composed of silica. As a result, algae get a suitable place for growth and become noticeable in a wide range.

Quick Solution

Use a siphon or a gravel vacuum to remove algae from sand and silicate. Which algae cannot grow due to the presence of silica?

2. Shortage of Light

Poor light supply can increase brown algae growth on the sand. They don’t need too much sunlight. As brown algae don’t need much sunlight for their photosynthesis, they like to stay in shady places and grow enormously where sunlight is not adequate.

Don’t keep your sandy land in a dark place. Make sure that enough sunlight is supplied to the sand.

3. Presence of Phosphate Level

Increased phosphate level is also responsible for algae growth. If the amount of phosphate level is more than 0.2 mg/L, it initiates algae growth.

Phosphorus helps in the tissue growth of brown algae. As a result, they can easily grow on sand.

Quick Solution

Try to keep the phosphate level less than 0.2 mg/L to avoid brown algae growth.

4. Increase in Nitrate Level

While nitrite is captured from ammonia through the nitrogen cycle, it gets turned into nitrates. But excess nitrate level supplies enough food for algae that facilitate algae growth on the sand.

In a nutshell, if you keep proper food for algae in the sand, it will grow more and more.

Quick Solution

Try to keep the nitrate level less than 20 ppm to prevent brown algae growth.

How Long Does Brown Algae Take to Grow

It’s around 1 to 3 weeks when brown algae grow perfectly on the sand. Under favorable environmental conditions, if the nutrient is supplied properly, they can grow restlessly. Mostly, they cover the whole nutrient-enriched area in 3 weeks.

How to Get Rid of Brown Stringy Algae on Sand

Use Gravel Vacuum in Aquarium

Now, come to the point of how to get rid of brown stringy algae on the sand. You can follow several steps that appear to be easy for you.

Siphoning With Gravel Vacuum

Though removing brown algae from sand is tough, some technical steps can help you in this case. 

  • Place the vacuum above the surface of the sand (Our Pick: hygger Aquarium Gravel Cleaner)
  • Continue the hose with a little suction.
  • Siphon the sand by vacuum to lose and break the layer of brown algae. 
  • Suck as much algae as you can.
  • Repeat the process until the whole brown algae layer is cleaned.

Kill Brown Algae Through Animals

Some species take brown algae as their food and thus keep the sand clean. Freshwater species like Amano shrimp, otoclinus catfish, nerite snails, etc., and marine water species like trochus snails, Mexican turbo snails, etc. can eat brown algae from the sand.

Nassarius snails are specially suggested for this purpose. Try to use it according to your need.

Bleach Solution

Here is another solution for you. Using bleach is beneficial if you want to get rid of this notorious thing. Spread bleach on the sand and soak it perfectly. It will destroy the growth of brown algae.


This is nothing but simply stirring the sand at a regular interval of 5-7 days. Meanwhile, the growth of brown algae will be stopped.

Algae Cleaner

Algae Cleaner is a two-way magnet that helps to detach the algae from the sand. Though it is more helpful outside of the aquarium, you can try this for sand purposes too. (Our Pick: Aqueon Aquarium Algae Cleaning Magnets)

Algae Control Solution

It is helpful for the algae that cannot be removed mechanically. Pick up an algae control solution and soak sand in that. Hopefully, brown algae growth will be stopped. (Our Pick: API ALGAEFIX Algae Control)

Leave It Alone!

You can be shocked by this solution. But don’t worry. Doing nothing may sometimes be a great thing. Sometimes algae grow at the first placement of sand in an aquarium.

You may wait for some days in this case. If they don’t get proper food and favorable conditions, the algae growth will ultimately be destroyed 

How to Prevent Brown Stringy Algae on Sand

To prevent algae growth on the sand, you have to erase the elements that feed or facilitate algae. Get an overall idea about this topic from here.

Phosphate Remover

This is the most prominent fact that you have to follow if you want to keep the sand free from brown algae. You may take the help of phosphate remover so that the silicate level remains down.

As silica is auspicious for algae growth, it can regenerate there easily. By using phosphate remover, phosphate removing filtration media such as activated alumina, GFO, etc. eliminate silicate.

Pure Water

You have to keep the water clean so that algae growth can be prohibited. In this case, you can notice the TDS value that should be around 1500 to 2000 ppm.

As TDS contains mineral constituents, it prevents the growth of organic pollutants. Thus, you can prevent brown algae growth.

Earthing up

Earthing up means the uplifting of sand from below the surface and sending the surface sand to the below portion. Performing this at a regular interval of 4-5 days won’t allow algae growth.

By exchanging the sand to a surface and sub-surface, the nutrient level and silica get changed continuously. As a result, the algae cannot grow properly. 

Change the Water

While changing water, unwanted or poisonous things are changed continuously. Besides, the sufficient flow of water keeps the sand clean. As a result, brown algae cannot expand their layer on the sand.

Change the water every week if you can. This would be beneficial to prevent algae growth.

Enhance Light Condition

Make sure of complete light conditions continuously to check brown algae growth. As they prefer dark zones, a moderate light supply will be disturbing for them.

UV Filtration

It is an updated and outstanding way to prevent the continuous outbreak of brown algae. When you add a UV filter to your aquarium, the radiation will go through the cells of the algae created by the UV bulb. Consequently, the algae layer will be devastated.

How Dangerous Brown Algae Can Be

Brown algae can be dangerous or deteriorate the look of sand especially if it is white sand. Many people use white sand to increase the beauty of their aquariums or fish tanks. Brown algae devastates the look by creating a nasty layer on it.

On the other hand, it may be considered an organic pollutant. It affects the water and creates a bad odor and color in the water. As a result, you cannot keep the water clean.

But, brown algae has no direct effect on fish. They don’t create any poisonous substance that may cause harm to the fish.

Can Brown Algae Come Back After Cleaning?

Yeah! Brown Algae may come back though you have cleaned it properly. In case of proper food availability, it will again appear in your sand.

Every year, great brown algae bloom occurs if you cannot mitigate their nutrient, especially phosphorus levels. That’s why you need to keep your tank water pure and clean.

Fortunately, if you continuously keep changing your tank or aquarium water for 6-8 weeks, hopefully, brown algae growth will be stopped. But you need to stop them during their reproductive stage every year. Otherwise, they will come back and destroy the look of your tank.

Brown Stringy Algae With Bubbles

Brown stringy algae with bubbles generally indicate dinoflagellates. Dinos are composed of cellulose materials whereas diatoms consist of silica materials in their cell wall.

Again, diatoms have a higher mobility rate than dinos. The bubbles are mainly the expression or release of oxygen while going through photosynthesis. If you find bubbles on the brown layer, consider them as dinoflagellates. 


To remove dinoflagellates from your sand,

  • Lower the nitrate level to 3-5 ppm
  • Maintain low light condition 
  • Maintain phosphate level between 0.07-0.15 ppm
  • Keep the temperature between 81-82°F.


Does Brown Stringy Algae Grow In A Freshwater Aquarium?

Usually no! If the water of the aquarium is pure, algae cannot grow. But due to the presence of their food, you can still find them.

What Temperature Do Brown Algae Grow?

As there are many species of brown algae, the temperature range varies. But you can assume 18 to 28°c is perfect for brown algae growth. 

Does Brown Stringy Algae Grow On Coral?

Yes! They can grow on coral and cover the entire place of that thing destroying its beauty.

What Are Examples Of Brown Algae?

Around 1500 species are found under brown algae. Among them, diatoms, dinoflagellates, fucus, etc. are common examples.

Final Thoughts

Finally, we are going to wrap up our entire discussion. Those who are aquarium holders, almost all of them face the problem of brown stringy algae on the sand. As we mentioned earlier, you just need to resist all the factors of their growth, gradually they will appear.

In a nutshell, for better performance, you may try a combo of several methods. That’s totally up to your needs. So, complete the procedures and keep sand free from this brown film. Thus, you can get a beautifully decorated aquarium.

Howard Parker

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