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How to properly clean a fish tank

Woman cleaning the inside of a fish tank with a sponge cleaner

There are few things worse than living in a constantly dirty home. Now just imagine how a fish feels when its tank is dirty. Fish eat, sleep, swim, and ‘breathe’ in their entire surroundings. If a fish tank is not kept clean it can seriously harm the health of the fish. Not only does a dirty fish tank make your fish unhappy, but it can also look unsightly in the home. It’s crucial to keep your fish tank clean for the health of your fish, and the overall cleanliness of your home. However, do you know that you are following the right steps to clean your fish tank? Keep reading to find out how to properly clean a fish tank. 

Why you need to clean your fish tank

It’s difficult to feel your best when you’re in a dirty space. It can be more difficult to relax and feel comfortable when you feel like your surroundings are unsanitary. The same goes for your fish. Fish are constantly fully immersed in and breathe in their own waste, discarded food, bacteria, and algae. Though there will always be a certain amount of waste in the tank, the levels can be controlled and maintained to keep your fish in their best health. Bacteria, nitrate, and algae levels that are imbalanced with the amount of clean and oxygenated water can threaten the life of your fish, as well as make your tank appear and smell dirty. Just like you should pick up after your other pets, the same should be done for your fish. It’s important to keep your fish tank clean to maintain the health and wellness of your fish. 

Man cleaning the outside of a fish tank with a microfiber cloth

How often should you clean a fish tank?

Maintaining a fish tank can be complicated, and will be varied for every tank. A number of factors will come into play when determining how often your fish tank should be cleaned, like the size of the tank, the number of fish in your tank, the nitrate levels in the water, and the method of cleaning. Because every tank is so unique, there is no one answer to the question of how often you should clean your tank. Every tank will require special care instructions to keep it at its healthiest. 

To decide when it is time to clean your fish tank, you will likely need to test the water for nitrates first. This is particularly important when changing water. If you’re simply cleaning the outside of the tank, or scraping away excess algae, you may be able to skip nitrate testing. Always, however, check with your veterinarian for the best instructions when it comes to caring for your tank. Nitrates in your tank are produced from the bacteria caused by fish waste and discarded food. If the nitrate levels are too low or too high, it can negatively affect the health of your fish. Algae levels in your tank can contribute to oxygen levels in the water which will also affect your fish[3]. By changing the water in the tank you can control nitrate levels. Changing too much water can shock your fish while changing too little water can have little effect on the nitrate levels. It’s a delicate science, which is why testing the nitrate levels before changing water is crucial. 

Cleaning a fish tank too frequently can stress your fish out, but not cleaning frequently enough can leave your water stagnant and loaded with bacteria. The exact time period you choose to clean your fish tank can differ depending on the filtration system, breed of fish, the size of your tank, and nitrate levels. Depending on these factors, you can clean your fish tank anywhere from twice a week to once a month[1]. For the sake of routine, the average tank should be cleaned about once a week, and have a deep clean and water change about once a month.  Again, always follow the advice of your aquatic veterinarian when it comes to your cleaning schedule. 

What you will need to clean a fish tank

Your fish tank may have special needs. Depending on your filtration system, type of fish, number of fish, and other factors, your tank may require different cleaning solutions. Always get the advice of your aquatic veterinarian. Typically, most tanks will require the following to be properly cleaned

Nitrate testing kit:

Nitrate testing kits namely allow you to test the level of nitrates in the water caused by bacteria. The level of nitrates shown on the test will indicate the percentage of water to be replaced to maintain a healthy level.

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Algae scraper sponge:

An algae scraper sponge is used to scrape excess algae off the sides of your tank. While a certain amount of algae in a tank is beneficial to its balance, excess algae can actually begin to trap oxygen, depriving your fish[3]. An algae sponge scraper will help you maintain the algae and oxygen levels, and give your tank better visibility.

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Aquarium vacuum:

Aquarium vacuums are the most efficient way to clean the gravel in your tank. It will vacuum up discarded food and fish waste trapped in the rocks, and excess algae. By using an aquarium vacuum you can avoid having to remove the rocks and wash them by hand. 

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How to properly clean a fish tank

Cleaning a fish tank can be a delicate process. It’s important to clean your tank without killing all of the beneficial bacteria that also inhabit it. By following these steps and the advice of your aquatic veterinarian, you can get your aquarium looking great, and your fish feeling their best. 

Step 1: Cleaning the aquarium glass

First, start by cleaning the glass on the inside of the aquarium with an algae scraper sponge. For any stubborn build-up on the tank glass, you can use a razorblade or hard plastic scraper if your tank is acrylic. You should clean your aquarium glass weekly. 

Step 2: Cleaning tank rocks and decorations 

The next step is to remove any decor from the inside of the aquarium that has a build-up of algae. Clean the ornaments with an algae sponge and warm water. Do not use a regular sponge as this may contain traces of harsh chemicals. Also, do not use any soaps when cleaning tank decor as this can be very hard to completely remove, and can be extremely harmful to your fish[2]. Just stick to warm water, an algae sponge, and elbow grease. You should clean your tank decorations every time you notice there is an excess of algae.

Step 3: Vacuum aquarium gravel

With your tank decorations cleaned and out of the tank, use an aquarium vacuum to siphon up any trapped fish waste, discarded food, and debris from the gravel. Vacuum the entire surface of the tank. If your aquarium vacuum replaces the discarded water with clean water, make sure that this water is at the same temperature as the water in the tank, as a drastic temperature change can cause stress to your fish. You should clean your aquarium gravel every time you do a water change to rebalance nitrate levels. 

Step 4: Test nitrates, and change water if necessary

After vacuuming the gravel, some of the water will have been replaced through that process. Test the nitrate levels in your tank to determine if additional water should be changed. For a monthly water change, 25% is a good amount[2]. If your vacuuming process changed less than 25% of the water you can change more water if your nitrate levels are still too high. 

Step 5: Clean the outside of the tank

The outside of your tank can be cleaned as frequently as you wish. You can clean the outside of the tank with a designated aquarium cleaner or a mix of vinegar and water. For the tank lid, hood, and any lighting, you should use also use a designated aquarium cleaner, or a mix of vinegar and water followed up with a rinse from a clean damp cloth. 

Step 6: Cleaning the filter

Your filter should be cleaned 2 weeks after you perform the previous steps. Beneficial bacteria can be trapped in the filter and redistributed into the tank. If you clean the filter at the same time as cleaning the rest of the tank, you could destroy beneficial bacteria cultures in the water which eliminate toxins in the water. By waiting 2 weeks before cleaning you allow the beneficial bacteria in the water to become balanced again. You should clean your filter once a month. 


Article Sources:

  1. Animal City. “How Often Should You Clean Your Fish Tank” 
  2. The Spruce Pets. “How to Clean a Dirty Fish Tank
  3. Swell UK. “How to get rid of algae in a fish tank naturally