How to Clean a Fish Tank

How to Clean a Fish Tank
Cleaning a Fish Tank

Cleaning a fish tank is an essential part of maintaining a healthy environment for your aquatic pets. Regular cleaning helps remove excess waste, debris, and algae, ensuring that the water stays clear and the fish thrive.

How to Clean Your Fish Tank

Here’s a list of materials needed for cleaning your fish tank:

  • Bucket: For holding and transporting water.
  • Algae Scrubber or Pad: For cleaning algae off the glass.
  • Gravel Vacuum or Siphon: For removing debris from the substrate.
  • Water Conditioner: To treat tap water and remove chlorine or chloramine.
  • Clean Cloth or Sponge: For wiping down the outside of the tank.
  • Pruning Tools: Tools such as scissors may be needed to prune the plants.

Here’s a step-by-step guide on how to clean a fish tank:

1. Wash your Hands

It’s not always necessary to wash your hands before cleaning a fish tank. However, if you have contaminants or chemicals on your hands, this would be a necessary step. These contaminants can include lotion, fragrance, sunscreen, household chemicals, etc.

Clean your hands with soap and warm water. Choose a mild, fragrance-free soap. Avoid soaps with unnecessary additives as these can be harmful to fish. After washing your hands, it’s important to rinse off the soap from your hands completely. If necessary, you can rinse your hands with water twice to make sure the soap is completely off of your hands.

Depending on how deep your tank is, wash your hands and arms to your elbows.

2. Turn Off Equipment

Power down electrical equipment such as filters and heaters. This ensures your safety and prevents any disturbance while cleaning.

As a safety precaution, turning off aquarium heaters is very important. Since aquarium heaters are generally designed to operate in a submersed state, when they are left on even when they are outside of the water, some of them will break. In fact, some glass heaters are known to shatter under certain circumstances. Be sure to follow manufacturers’ safety guidelines.

3. Clean the Inside Walls

Use an algae scraper or a sponge to gently clean the inside walls of the aquarium. Remove any algae or debris, taking care not to scratch the glass or acrylic.

If you have a glass aquarium, glass-safe scraper blades will easily cut through algae.

4. Prune the Plants

Trim any dead or overgrown parts of aquatic plants using aquarium scissors or pruning tools. This helps maintain a healthy and aesthetically pleasing environment.

5. Clean the Hardscape and Decorations

Remove any decorations or hardscape items from the tank. Scrub them gently with a soft brush or sponge to remove algae or debris.

Rinse the decorations in a bucket of aquarium water. Avoid using tap water or soap, as it may contain chlorine or other chemicals harmful to fish. Rinsing in aquarium water helps preserve the beneficial bacteria that may be present on the decorations.

6. Vacuum the Substrate

Use a gravel vacuum or substrate cleaner to siphon out debris and detritus from the substrate.

To start the gravel vacuum, place a bucket on the floor in front of the aquarium. Next, place the gravel vacuum or aquarium siphon into the aquarium. Try to get all the air bubbles out of the inside. You can start the siphon by sucking on the hose end with your mouth, but be careful not to get a mouthful of dirty fish water.

To vacuum the substrate, push the siphon into the gravel or sand, and let it start vacuuming up some of the substrate. If your substrate is too deep (more than two inches), vacuuming may not be sufficient to clean the deep layers. Stick the rigid tube into the substrate and allow a few seconds for the sand/gravel/rocks to be pulled into the tube. Before they get more than halfway to three quarters into the siphon, pick up the tube and allow the substrate to fall back down. Move the vacuum through the gravel or sand, making sure to clean all areas.

Vacuuming removes the small particulates from the substrate, which is mostly made up of fish waste, dead plant material, and excess food. By removing these particulates before they break down, you will decrease the ammonia concentration in your aquarium.

7. Clean the Filter

Cleaning an aquarium filter is important, because it ensures the filtration system is working properly.

Start by turning off and unplugging the filter system if it hasn’t been done already. Siphon tank water into a clean bucket and use it to gently rinse solid debris off of filter pads, sponges, or bio-media. Do not use soap. If you have a multi-sponge filter or more than one filter system, only rinse one sponge or one filter per cleaning to preserve bacteria levels.

If you’re replacing the entire filter, reuse an old filter media or keep the old filter in the tank for a couple weeks to supply the new one with bacteria. Scrub the non-media parts of the filter thoroughly with the tank water. Use a small cleaning brush, sponge, or filter floss to clean the impeller, the impeller housing, and the filter housing.

After cleaning, install the filter back on the aquarium, partially fill the filter with aquarium water, then replace the cover. Plug the filter in and turn it on. You now have a clean filter.

Remember, preserving tank bacteria when you clean or replace filters is an important but easy task.

While this depends on the tank’s bioload, it’s generally recommended not to let more than a month pass between cleaning and maintaining your filter.

8. Refill the Water

Use a water conditioner to treat tap water before refilling the tank. Add water slowly to avoid disturbing the substrate or decorations. Ensure the water temperature matches the tank temperature. This will help avoid causing stress to the fish.

9. Turn On Equipment

Switch on the aquarium equipment, including the filter, heater, and lights. Allow the water to circulate and stabilize.

10. Test the Water Quality

Use a water test kit to check parameters such as pH, ammonia, nitrite, and nitrate levels. Adjust water conditions if needed to ensure a healthy and stable environment for your fish.

11. Wipe the Glass

Finally, use a clean, aquarium-safe glass cleaner or a mixture of vinegar and water to wipe the exterior glass surfaces. This adds a finishing touch to the cleaning process and enhances the visual appeal of your fish tank.


Here are some frequently asked questions related to cleaning fish tanks:

How often should you clean a fish tank?

The frequency of cleaning a fish tank can depend on several factors such as the size of the tank, the number of fish, the types of fish, and the filtration system. Here are some general guidelines:

Partial Cleaning: A fish tank should be partially cleaned once a week or bi-weekly. Generally, this involves changing about 10-20% of the water. Always keep the nitrate levels below 40 ppm.

Thorough Cleaning: Approximately once a month, a fish tank should undergo a thorough cleaning. Perhaps, the filters should be cleaned during this time. With that said, completely replacing the water in the fish tank is not recommended as it will remove beneficial bacteria that live in the tank and reset the nitrogen cycle, which could harm your fish. Occasionally, when plants, rocks, or decorations become visibly dirty, you will want to clean them.

Please note that these are general guidelines and the specific needs of your fish and tank might vary. It’s always a good idea to monitor your fish and their environment closely and adjust your cleaning schedule as needed.

How much water should I change in the fish tank?

As a general guideline, many aquarium hobbyists recommend changing 10-20% of the water in the tank every 1-2 weeks. However, the tolerance of how much the fish can handle can vary depending on the type of fish, size of aquarium, and stability of the aquarium. Some fish, especially fish that are well-established, may be able to handle larger water changes. For example, some fish are able to handle weekly water changes of 50% or more.

One factor to consider is how often the water changes have been performed. If water changes have been done consistently in the past, and the fish are used to large water changes on a regular basis, those fish may have an above average tolerance. If the water parameters of the water in the fish tank and the new water is nearly identical, it may be possible to perform larger water changes.

However, if the water in a particular fish tank hasn’t been changed for a long period of time, water changes should be done with caution. While you may feel the urge to do a large water change on a dirty tank, it may actually do more harm than good to the fish. In that case, performing small water changes of 10% or less, and allowing the fish to gradually acclimate to the clean water may be beneficial.

If the water parameters in the tank water is significantly different than the new water, this may cause a lot of stress to the fish.

How long does it take for an aquarium water conditioner to dechlorinate the water?

The time it takes for an aquarium water conditioner to dechlorinate the water can vary depending on the specific product and its formulation. In general, most water conditioners work relatively quickly, and you can often expect the dechlorination process to occur within a few minutes.

It’s essential to follow the instructions provided by the manufacturer on the product packaging. The recommended dosage and contact time can vary, so be sure to adhere to these guidelines for optimal results. Some water conditioners may also address other water quality issues, such as neutralizing heavy metals or promoting the growth of beneficial bacteria.

If you’re in doubt or have specific concerns about the dechlorination process, you can test the water with a chlorine test kit to ensure that the chlorine levels are within the acceptable range for your aquarium inhabitants. Always prioritize the well-being of your fish and other aquatic organisms by maintaining a healthy and stable water environment.

Why is my fish breathing heavy after cleaning the tank?

There could be several reasons why your fish is breathing heavily after cleaning the tank:

Chlorine: The new water that was added may not have been properly dechlorinated, causing the fish to suffer. Ensure that a water conditioner was used to properly treat the tap water.

Ammonia or Nitrites: Cleaning a fish tank, especially vacuuming the substrate, will involve some level of agitation. This agitation may have caused ammonia or nitrites that were buried in the substrate to enter the water column. Once the debris settles, the ammonia and nitrite level may return to normal. Otherwise, if you can perform water changes without further agitating the substrate, this may help reduce the ammonia or nitrates.

Water Quality: There may be issues with the new water that was added. There may have been significant differences in the water parameter or it may have contained contaminants. The water should be tested for any detectable abnormalities. Incorporating activated carbon in the filtration system may help absorb some toxins in the water.

Stress: The fish may have been placed under stress due to the disruption during the cleaning process. Allowing some time for the fish to relax may help.

If the problem persists, consider consulting a professional for proper diagnosis and treatment.

How Can I Clean Hard Water Build-up on Fish Tanks?

If you have hard water, you will notice the hard water build-up or calcium deposit on the edge of your fish tank. These white water stains will be often visible on the aquarium glass, right above the water surface. In most cases, you can clean this off with a wet sponge or paper towel. Simply wet the sponge or paper towel with tank water, and wipe it off. Some light scrubbing may be required, but it shouldn’t be difficult.

If the hard water build-up is stubborn, and it doesn’t come off even after scrubbing, you can use a mixture of water and white vinegar. Mix one part white vinegar with one part water. Since vinegar is acidic, it will help remove these calcium deposits. While vinegar is safe for aquariums when used in moderation, it’s best to avoid it from entering the fish tank unnecessarily.

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