Algae, Aquarium Plants

How to control Algae in Planted Aquarium

The internet swarms with techniques where one can overcome the slimy greens. Before we find ways to curb algae, one must realise that the growth cannot be completely eradicated. We can take multiple measures that can help us control them, as this is a normal process.

How to control Algae in Planted Aquarium
Algael bloomed tank

A common misconception is that algae is green and grows on tank walls. This is not right, you could be facing a greenish, brownish or even a reddish remnant that squirms along the walls of the tank, gravel, chips, rock, aquarium accessories and even on aquatic plants.

Before we check out the factors that triggers the growth, lets look into the kinds of algae that we deal with. 

1. Brown– If you have a new tank, then you come across which are  easily wipeable, harmless and goes away as the tank gets matured.

2. Blue-Green– Also known as cyanobacteria. These spread rapidly and in most cases are quiet difficult to control. An overabundance of phospate and nitrate in water makes way for these slimy unwanted guests.

3. Red– This is the most resilient of all and materialises on plants. Get rid of these by dunking the plants in a bleach solution for couple of minutes for a week.

4. Green– This is the healthiest of all algae that the algae-eating fish/shrimp feed on.

Going by the name spot algae, you need not worry if you frequently take care of your tank.

Apart from the above, one could face a rare phenomenon called the algae bloom (green water). This is the most annoying to get rid off as they cannot be scrapped off from surfaces. A complete shutdown of light for few days and using a diatomic filter is mandatory to defeat the bloom. Merely changing water won’t help as chances of regrowth are high. Ensure to test water for nitrate, ammonia, nitrite and phospate as these paves way for algae growth.

Now that we know the different kind of algae, lets look into the factors that triggers these growth and the measures to curb them. The four common factors are:


When we talk about light, we often speak about aquarium lights alone, a common mistake people make is ignore the sunlight. Ensure not to place your tank where there is direct sunlight (even if it is for part of a day). Sunlight promotes algae growth. Aquarium lighting plays a major role, they have a PAR (photosynthetic active radiation) value. This value determines the amount of light required by plants for photosynthesis. Each plant has its own PAR value. For intance, plants such as ferns, moss, anubias, bucephalandra etc requires only 15-30umols* of PAR. Moneywort, Java ferns, Rotala Rotundifolia etc requires 160-200umols* of light. High PAR levels may pave way for algae. A good CO2 system and controlled PAR levels can ensure healthy plants, thereby hindering algae growth.

*PAR levels mentioned are approximate values

One must also consider the duration an aquarium light is used. An average tank requires only about 6-7hrs of light, where as new tanks require much less, between 4-5hrs. 10hrs and above can not only harm your plants but also trigger algae growth. Consistant hours of light is required for a healthy tank. Changing the hours every now and then can also cause harm. Set a timer and use auto adjusting light that can turn on/off on the hours required.

Healthy Plants

A healthy plant requires adequate amount of carbon, nutrients, light and flow. Low Co2 level is considered to trigger many algae growth, this does not mean that higher levels of Co2 can kill algae. A well maintained tank can slow the process of unwanted slimes this is one reason why most people prefer a densely planted aquarium right from the start. Each tank may have its own recommended plant mass, you can check with our experts to know how much plant is required for your tanked based on its size. Planted aquarium with substrate of 2inches (approx) are able to withstand algae. Larger plants are more resilient to algae than smaller ones like moss and carpets. Plant growth, tank design and flow patterns are also factors that can curb the presence of algae. There are times when one can find algae etched to certain areas of the tank because of the flow pattern. Having deep rooted plants can help you overcome these issues.  Remove decaying leaves and vacuum if you have gravel/substrate from time to time. As your plant grows, ensure to prune them. New growing plants are heavily resilient to algae.


Know your water. The simple and most important way to avoid any kind of algae is to frequently change water. You can either do this on a weekly or bi-weekly (once in 2 weeks). Make sure you drain your entire tank. Changing 20-25% of water is optimal. keep a tab on the nitrate and phospate levels in your water. A prime level would be 5-10mg of nitrate and 0.1mg phospate. Excess of these can be removed by proper filtering system.


Set up a good filtering system for your tank. As mentioned above the level of nitrate and phosphate can be tuned with proper filtering system. The flow of filter plays a vital role as well. Turning off filter at night on a regular basis may lead to algae blooms. A good filtering system aerates the tank well making way for quality bacteria that is required a healthy, algae free tank.

Biological Factors

The most efficient way to control kelp is to add algae eating fish, shrimps, snails and micro-fauna that feeds on algae and help break down debris. Live plants can absorb nutrients that these algae thrive upon. Fewer nutrients in water means, lesser fuel for algae overgrowth.

The above are most common precautions taken by hobbyist to control algae. Even though these factors can curb the growth, only a timely and consistent check can help you maintain a good and healthy tank.

Remya JKumar is a Blogger by interest, Chef by choice, Dancer by art

Leave a Reply

Your email address will not be published. Required fields are marked *