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How to Prevent Algae in Aquarium – Complete guide with the most common algae

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by Jason Matthews



Did you know uncontrolled algae growth in an aquarium can be hazardous to fish? As much as algae appearance in aquariums depicts well balanced and healthy aquariums, it may negatively impact aquarium watercolor, cover the decorations/ inhabitants, or diminish the appeal of the entire environment. Thus, keep intact as we peruse on how to prevent algae overgrowth in an aquarium.

Deterring algae in an aquarium can be achieved through performing regular water changes. Change 10 to 15 percent of aquarium water every week so as to lower the nutrient levels in the water. Additionally, placing your aquarium in areas with minimal direct light aid in preventing algae. Alternatively, keep the organic waste low and practice good vacuuming techniques to remove detritus.

Algae may appear as greenish, brownish, or reddish residue inside the aquarium. Algae growth thrives underwater, light, and nutrients. Scroll within the post to get a comprehensive perusal of some of the common reasons for algae overgrowth and preventive measures to keep algae growth under control.

Methods to Prevent Algae in Aquarium

Portion control

Frequent feeding of fish may initiate overfeeding. If the fish hasn’t eaten provided food within 3-5 minutes, you have given excess. Have a limiting schedule that feeds your fish once a day or multiple times a day in minimal amounts.

Nutrients in food encourage the growth of algae. Since removing what they don’t finish is tedious, cut back the amount of food to prevent algae growth.

Dim the lights

For algae to flourish, it requires plenty of light; thus, put your aquarium somewhere with less direct light. Move your tank to a shadier spot away from windows. Don’t leave lights on in the room for more than 8-10 hours a day.

Ensure you integrate thick curtains to reduce the amount of sunlight penetrating. Alternatively, you can integrate a timer for your aquarium light to have better control over light exposure.

Change the water

10-15 percent water change ensures the nutrient levels are balanced. Prolonged aquarium water accumulates nitrate and phosphate, which contribute to algae growth. Perform a partial water change each week to minimize algae.

Water change focuses on diluting aquarium water with fresh water, removing impurities without shocking the fish/plants.

Add live plants

Amalgamating green plants within the aquarium not only do they bring attractive features but also help compete for light and nutrients that lead to the thriving of algae. There is less for algae to intake for growth. Trim decaying parts and leaves to deter water pollution.

Scrape Away

Use a scraper regularly to remove the buildup of algae on the glass sides of your tank. Algae sticks on the scrapper, allowing you to remove it at ease. Scrape any visible algae growth on glass, rocks, or tank surfaces. Remove the rocks and scrub them. Additionally, vacuum the gravel when undertaking water changes.

Test your water

Test your aquarium water using Aquarium Test Strips to determine what is present. Know the water PH, nutrients, and mineral levels. Knowing your water helps you understand what changes to make. If your water source is high in phosphate, consider using phosphate removing chemicals.

We’ve made a guide to identifying the symptoms of low pH in aquariums

Consider adding algae-eating fish.

Fish breeds such as Dwarf Otocinclus Catfish, Plecostomus, Cory Cat, and Siamese flying fox survive feeding on algae and leaves. Prior to incorporating them in your tank, ensure they are compatible with another fish type present in the aquarium. Algae eaters promote a healthy tank ecosystem.

Use high-grade filters and media.

Algae thrive on the availability of excess nutrients. Appropriate filter media makes a significant difference in phosphate levels. Poly filters and pre-filters aid in removing phosphate, iron, and heavy metals, thus slowing the generation of algae. Use of premium-grade carbon aid in minimizing dissolved organic metals.

What Causes Algae Overgrowth?

Algae growth is promoted by the presence of water, light, and nutrient necessities. When these variables aren’t controlled, algae can grow like wildfire. Other elements that boost algae overgrowth in aquariums include;

  • Overfeeding the fish
  • Aquarium in a location with too much sunlight
  • Too much lighting exposure
  • Maintaining a water ecosystem with high nutrient value
  • Going too long between water changes

Common Types of Algae Occurring in Aquariums

Name of AlgaeCausesSolution
Green Spot AlgaeToo much light, excess organic debrisRegular partial water changes & cleaning, feed less
Hair algaeNutrient imbalance, CO2 fluctuations, too much lightAmano shrimp, balanced nutrients
Black Beard Algae (BBA)CO2 fluctuations, Too much lightLiquid Carbon, BBA-eating fish
Blanket Weed (filamentous algae)High pH, Too much light, excess nutrientsRemove by hand, adjust nutrients
Blue-Green Algae (BGA)Low current, constant lightRemove with algae scraper, partial water changes, clean filter
Brown Algae (Silica algae)Too low light, too high nitrates, excess silicatesWipe off, vacuum the gravel, sucker-mouth fish, Change water partially
Green Water AlgaeToo much light, Nutrient imbalance, infrequent water changesTemporarily remove light, diatom filter or UV sterilizer
Green Dust AlgaeHigh temperatures, too much light, excess organic debrisImprove CO2 levels, temporarily remove light
Fuzz AlgaeLow CO2 levels, Too high/low nutrientsCut and scrape off, lower light settings, Amano shrimps

Brown algae/ silica algae/ gravel: It is common in a new aquarium. It appears as a coated sheet on the tank and is easily wiped off. Brown algae are usually harmless and eventually disappear as the tank matures.

Blue-green algae/ smear algae/ slime: It is usually a cyanobacterium caused by an excess of phosphate and nitrate in the water. Slime spreads rapidly and can be challenging to control. But good water care and removal of excess nutrients can be imperative. Use Erythromycin against blue-green algae.

Red or beard algae: It appears on plants; thus, termed to be one of the toughest algae to clear up. Get rid of it by using a bleach solution for a few minutes.

Green algae/ Hair/ thread/ spot algae: it is a healthy type of algae commonly found in most aquariums. Algae-eating fish feed it. If your aquarium is well cared for, green algae won’t overgrow. Ideally, you can use some of the algae in your aquarium for control.

Green water/ algae bloom: Green water results from the growth of microscopic algae suspended in the water. It is a stubborn algae as it is frustrating to remove or wipe off. Counter green water using a diatomic filter and test the water for any ammonia, phosphate, and nitrate as the elements promote algae growth.

Tips to Getting Rid of Algae in Aquarium Water

  • Clean your plants

Algae may grow on the leaves and stems of your aquarium plants; hence, create a routine to clean them regularly. Use 5-10% bleach solution to destroy the algae as you dip the plants in the solution for a few minutes. Rinse the plants thoroughly because bleach can kill your fish.

  • Care for your aquarium water

Routinely, check the water at least weekly. Pay attention to PH levels and measure levels of relevant nutrients.

Read our guide to lowering pH in fish tanks

  • Invest in a filter

Combating algae growth and persistent regeneration can be easily countered through the integration of a diatomic filter—the filter aids in removing algae from the water consistently.


Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

Jason aquariume

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