How to Clean Algae off Aquarium Gravel

Seeing a sudden algae bloom in your fish tank is never a good thing. Wherever there is light and water, algae will grow on aquarium gravels and rocks over time. These dirty gravels can toxify the new water if not cleaned properly.

This is not only bad for the aesthetics of your aquarium, but the algae could also harm your fish and plants. 

In this guide, we will present some effective methods with tips and tricks to clean algae off the aquarium gravel, so your fish remain healthy and happy.

Causes of Algae Growth on Gravel

Heavy algae growth in the fish aquarium can compromise your water’s pH and your fish’s oxygen consumption. There are various reasons that can result in algae blooms in your fish tank. Let’s discuss each in detail. 

Lack of Maintenance

Owning an aquarium comes with responsibility. Without proper maintenance, you can’t expect the tank to remain clean and alluring. A gravel vacuum should be incorporated into the aquarium to remove dirt and debris at regular intervals. 

The gravel vacuum turns over the gravel, limiting sunlight exposure and ultimately killing algae. Also, it removes the food residues and debris that are a prime source of nutrients for algae in the aquarium.

Extended Light Exposure

Excessive exposure of aquariums to light can lead to a heavy algae bloom. If you don’t have light-dependent organisms and corals in the tank, it is highly recommended to shorten the light exposure. This will decrease algae growth and keep your aquarium nice and tidy.

High Nitrate or Phosphate Levels

Nitrate and phosphate levels affect the algae levels in the aquarium. Nitrates are the end product of the nitrogen cycle that is directly used by algae as a food source. The moment you become careless about the maintenance, there could well be a rise in the nitrate levels, which means more food for the algae to flourish. 

Phosphates are commonly present in the water source, and the best alternative to reduce their level is to find a new source of water. Other factors like overstocking and overfeeding also increases the phosphate levels in the water.

Methods to Clean Algae off Aquarium Gravel

There are two methods employed to remove algae from the aquarium gravel; with vacuum and without vacuum.

How to Clean an Aquarium With a Vacuum Kit

A siphon is used to vacuum aquarium gravel. It features a plastic tube that uses hydrostatic pressure and gravity to suck debris from the gravel and dispose of it outside the aquarium. 

Follow this step-by-step guide to effectively use this vacuum to remove algae. 


Before starting, unplug the aquarium heater, filter, air pump, and light. There is no need to remove the aquarium decorations, plants, and fish from the aquarium. It is recommended to complete the process as soon as possible as the delay could stress your fish too much.

Get Things Ready

Assemble your gravel vacuum kit and place a water bucket below the aquarium to empty the dirty water solution. Slowly submerge the vacuum kit into the water. Make sure there is no bubble formation inside the tube. 

Remove Water

Cover the top of the tube with your thumb and move the tube inside the water two to four times. Take it out and empty the water into the bucket below.


Once the flow is established, start moving the tube over the whole gravel to remove the algae and debris. Remove the dirty water with grime in the bucket. Moving the gravel vacuum further into the substrate for a thorough cleaning is better. Some old gravel and pebbles might get stuck into the tube during this process. However, they will fall back once you raise the tube.

Focus on the Dirtiest Group

Once you are done with the general cleaning, look for the dirtiest group of the gravel and repeat the vacuuming step. Keep the tube straight to remove the whole debris part intact.

Stop Vacuuming

Remove the tube from the water once the water level has dropped about one-third of the full height. Drain the water into the bucket and continue vacuuming till the desired results are achieved.

Plug Back In

Once the cleaning is done and you are satisfied, remove the tube and clean it. Plug in and place the heater, air pump, and filter in the aquarium.

Tips for Using the Siphon

  • The siphon tube must be placed at a higher level than the aquarium so the debris and water can easily flow out on gravity.
  • Use a bucket to dispose of the dirty water removed from the aquarium.
  • The kit won’t work correctly if bubbles form. Make sure to use it carefully.
  • Remove the tube from the aquarium only after it gets filled with dirt. 

How to Clean an Aquarium Without a Vacuum Kit

Cleaning the aquarium with a vacuum kit is difficult but entirely possible. Achieving the desired cleanliness requires a little more time and hard work. Also, the fish need to be moved to a new tank, and gravel is poured out, which can be quite stressful. Here are some ways to clean algae off the gravel without using the kit.

How to Clean Gravel With Bleach

You need to eliminate algae the moment you see it in the tank. While it may look a little today, it can potentially overgrow quickly and disturb the optimal conditions of your tank. Follow this step-by-step guide to remove the algae using bleach.

  • First, mix bleach and water in the proportion of 1:9. Make sure to wear gloves to avoid burning your hands.
  • Remove the fish and decorations from the aquarium with a great case so the fish won’t get stressed.  
  • Move all the living plants to one corner of the tank and put the gravel in a pan.
  • Pour the bleach into the pan and stir it a little bit. Leave them in the solution for 5-10 minutes, and then rinse off the bleach. 
  • Remove all the traces of bleach by rinsing off with cool water followed by warm water. Let the gravel dry and place them back in the tank. Add the equipment and fish in the aquarium as they were placed before.

How to Clean Gravel With Vinegar

Vinegar features disinfecting properties and thus can be used to kill algae from the grave’s surface. It can be used as an alternative to bleach as a more natural approach. Here’s how you can use it to remove algae from the aquarium.

  • Carefully unplug the tank devices and move the fish into a separate tank. 
  • Remove all decorations and aquatic plants.
  • Use a fairly sized container to put all the gravel in it. Rinse them with clean water.
  • Prepare a solution of vinegar and water in 1:1 proportion. 
  • Soak the filter, decorations, and gravel in this solution for at least 24 hours. 
  • After that, scrub the decorations, equipment, and gravel with a toothbrush to remove all residues of the algae. 
  • Gently wash them with vinegar and then water. Finish the process, try everything, and place them back in the aquarium. 

To Conclude

Though green algae are a good food source for some fish species, its overgrowth can deprive them of essential nutrients and ultimately kill them. Also, the algal blooms make the tank water look musky and green.  

Once you know everything about cleaning the tank, it becomes easy to regulate the algae levels. That’s it for the guide. Hopefully, you have a better idea about cleaning the gravel with or without a vacuum kit.

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