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How to clean your aquarium

How to clean your aquarium

When it comes to cleaning your fish tank, staying proactive is key. A fish tank is a delicate ecosystem, which can easily become toxic to its inhabitants if the right steps aren’t taken. Here’s how to keep your aquarium clean and healthy. 

Keeping your aquarium clean isn’t just about aesthetics - it’s essential for the health of your fish. In the closed environment of a tank, waste and leftover food break down, producing harmful substances like nitrate and nitrite, which are toxic to fish. Additionally, this waste buildup promotes algae growth, which competes with aquatic plants for nutrients and oxygen, disrupting the tank's biological balance.

Even if your tank doesn't look visibly dirty, these conditions can stress your fish, making them more prone to illness and shortening their lifespan. Maintaining a clean tank ensures a healthy environment where your fish can thrive. 

Before you get started…

Before diving in, lets answer some frequently asked questions: 

How often do you need to clean a fish tank?
How often you will need to clean your fish tank depends on your aquarium's size, the number of fish, the types of fish, and the filtration system you have. Smaller tanks and those with more fish will build up waste at a faster rate than larger, less populated tanks. As a general guide, most aquariums require a thorough cleaning (following all steps listed below) once a month, along with replacing 15-25% of the water every week. 

Weekly gravel vacuuming is also recommended to remove debris and maintain water quality. However, every tank is unique, so there's no one-size-fits-all answer. If you're unsure about the best cleaning schedule for your aquarium, ask the team at your local Animates for guidance.

Do you remove the fish from the tank when cleaning?

It’s best to leave the fish in the aquarium since you won't be draining it entirely, ensuring there's enough water for them to swim in. Removing them from the tank causes unnecessary stress for your fish, and you run the risk of accidentally hurting them.

What cleaning supplies do you need to get?

  • If you're new to fish keeping, here’s what you’ll need:
  • A large bucket (specifically for fish use to avoid lingering chemicals from mopping up in your tank)
  • An algae scrubber
  • Toothbrush for cleaning algae off decor or plants
  • Scissors for trimming plants
  • Water conditioner and treatment
  • Towel – just in case of any spills!
  • Glass-cleaning cloth or paper towel
  • Gravel vacuum
  • Test kit for checking the water parameters


Step 1: Wash your hands

Before you start cleaning, it's important to wash your hands and forearms up to your elbows. This removes any lotions, fragrances, or soap residue on your skin that could harm your fish.

Step 2: Remove algae

Start working on the inside aquarium walls first, with an algae scraper. Remove artificial plants, decor, rocks and scrub algae off with a clean toothbrush. You can do this in the sink or in your dedicated aquarium maintenance bucket, using some warm water. Leave the aquarium gravel in the tank.

Do not use soaps or detergents of any kind, as they are very difficult to fully rinse away and can be deadly to fish. 

Step 3: Prune the plants

If you keep live aquarium plants, take this time to remove any dead leaves and trim down overgrown foliage. If you have tall stem plants, you can easily propagate them by cutting a few inches off the tops and replanting them into the substrate.

Step 4: Turn off the filter and heater

Before removing any water, make sure to turn off or unplug all equipment, including the filter, air pumps and heaters. Aquarium heaters and filters are not meant to operate without water and therefore can become damaged when running in dry air.

Step 5: Vacuum the gravel

Over time, fish waste and leftover food can break down into fine particles called detritus, which settle between the gravel rocks and can harm your fish. To tackle this, you'll need a gravel vacuum, a handy tool that removes debris efficiently. It consists of a plastic tube attached to a siphon, which you use to draw water and waste from the gravel into a bucket. Think of it like using a vacuum cleaner for your aquarium!

Here’s how to do it:

  1. Submerge the gravel vacuum into the water, creating suction by using the siphon.
  2. Move the vacuum through the gravel bed, allowing the flowing water to dislodge and carry away debris trapped in the gravel.
  3. Continue until you've removed about 25% of the tank's water capacity, ensuring not to remove more as it can disrupt the biological filter.

You'll know you've cleaned enough when the water being siphoned out is clear rather than cloudy or grayish-brown. 

Step 6: Clean the filter

Regularly cleaning your filter is essential for maintaining a healthy aquarium environment. Think of your filter like a trash can that collects waste and debris from the water. Just as you empty a trash can to keep things tidy, the filter needs to be emptied out regularly to remove all the waste before it gets clogged up or overflows. 

To properly care for your filter, here are the key maintenance tasks:

  • Carbon: replace every six to eight weeks.
  • Filter cartridge: replace every six to eight weeks; these often contain carbon.
  • Sponges: clean every two to three months. Rinse them in treated water to preserve beneficial bacteria; tap water's chemicals can harm them.
  • Ceramic noodles: replace every six months to maintain the biological filtration.
  • Impeller and rubber diaphragms: replace if damaged.

If you're using a hang-on-back, canister, or corner box filter, rinse the filter media in your bucket of recently removed tank water. Avoid using soap, just plain water is best. For sponge filters, take out the foam part and squeeze it several times in the bucket of old tank water.

Step 7: Add new water

Now, it's time to refill your tank with fresh, clean water. But before you do, remember these important steps:

  • Make sure the new water is close to the same temperature as the water already in the tank, within the ideal range for your fish species.
  • Treat the water with a conditioner to remove harmful chlorine and chloramines commonly found in tap water.

First, empty the bucket containing the old tank water. Refill it with tap water and use a thermometer to check the temperature matches the tank's water. Add the water conditioner directly into the bucket following the instructions on the bottle. Now you’re ready to pour the treated water into your tank. Add it slowly so as not to run the risk of shocking your fish.

Step 8. Turn the equipment back on

Once all the water has been replaced, put your heater back into the tank, turn it on, and start your filter up again, too. Despite the effort you've put into cleaning, the water may initially appear cloudy due to suspended particles. Don't worry – within an hour or so after turning the filter on, the debris will settle at the bottom or be captured by the filter. 

Step 9: Test the water quality

After completing the cleaning process, it's important to test your aquarium water. By testing for parameters like ammonia, nitrite, nitrate, pH, and temperature, you can detect any imbalances that may affect your fish's well-being. It's best to wait for the tank to settle before testing - testing immediately after adding the water may give inaccurate results.

Use an aquarium water testing kit according to the instructions. Adjust water conditions as needed based on test results to maintain a stable and safe environment for your fish. If you are new to fishkeeping, bring along a water sample to your local animates for a free water test. 

Step 10: Wipe the glass

Lastly, take a moment to clean the outside of your aquarium, removing water spots and smudges for added clarity. Even though your fish won't touch these surfaces, it's still important to use a cleaner that's safe for aquariums. Many household glass cleaners contain harmful chemicals like ammonia, which can harm your fish. 

Instead, use plain white vinegar on a paper towel. It's affordable, non-toxic, and leaves surfaces nearly streak-free. Also, clean off the dust that has collected on the lid, light, and aquarium stand. Your aquarium is now picture-perfect!

If you have any questions about cleaning your tank or maintaining water quality, don't hesitate to speak with the knowledgeable fish experts at your local Animates store. 

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