How to Clean a Fish Tank – A Complete Step by Step Guide

How to Clean a Fish Tank

Unlike fish living in natural bodies of water where their ecosystem is kept balanced by numerous factors, your fish tank is an enclosed system that will need your help to keep it a healthy environment for your fish.

It is your responsibility to keep fish healthy, the conditions of the fish tank optimal, and the ecosystem in the fish tank balanced. Knowing easy tips on how to clean a fish tank helps you prevent your fish tank water from becoming harmful to your fish.

The Importance of Cleaning Your Fish Tank

Cleaning your fish tank is essential to keep your fish living and healthy. The more fish you have in a fish tank, the more often you will need to clean up.

Research the number of fish to have in the size of your fish tank, what combination makes the most sense, and how you can use helpers, such as plants and algae eaters, to help keep your fish tank clean and balanced. Knowing how to clean a fish tank is as much about knowing how to balance a fish tank as to scrub it.

Most people do not understand that an ideally cleaned fish tank is still a little dirty.

Not understanding how to clean a fish tank is one of the main reasons people skip this important step or do not attend to it as often as they should.

Regularly monitoring and cleaning your fish tank will help keep you in tune with how the ecosystem is balanced and will give you hints on how to create a healthier environment for your fish.

However, use caution when looking for instructions on how to clean a fish tank as many will harm your carefully set up ecosystem. Here are things to keep in mind when learning how to clean a fish tank.

Try Not to Tear Down

Sometimes, people wait so long to clean their fish tank that they are tempted to tear it all down and start again. We recommend against starting all over every time your fish tank is filthy.

If you tear down a dirty fish tank and scrub it all out with vinegar or the like, you have a sparkling clean piece of glass that may not support your fish.

Tearing down a fish tank eliminates all the beneficial bacteria that have set up. Even the dirtiest of fish tanks can be recovered with some dedication and work.

Set Up a Schedule

checking fish tank pH levels

Having a regular monitoring and cleaning schedule will make having a fish tank more pleasure and less work. Once you have a fish tank set up, monitoring and cleaning a fish tank becomes an infrequent and fairly easy task.

Most professionals will recommend checking pH levels, removing visible gunk with tools such as algae scrubbers, and doing a partial water change once or twice a month.

A regular cleaning schedule will reduce the overall work and also reduce the risk to your fish.


Recheck your fish tank weekly to ensure that all cloudiness has resolved and that your pH, water temperature, and salinity is where it needs to be.

Use a home testing kit or take water to a fish store to have it checked for pH, nitrite, nitrate, ammonia, and salinity. Check all equipment for proper functioning and check fish for injuries or signs of illness.

Knowing how to clean a fish tank is unhelpful if you do not know what a clean fish tank means. (Note – We recommend repeating these checks weekly to catch issues quickly.)

Remember the Three Rs

The three Rs are the essential basis for knowing what you are trying to achieve by regularly maintain your fish tank. They are: regulate nitrogen cycle, remove particulate organic compounds, and replenish minerals.

Fish tanks undergo a nitrogen cycle where ammonia from waste is converted by bacteria to nitrite. Getting to the nitrates is what you want your fish tank bacteria to achieve.

Ammonia and nitrites can be toxic and are difficult to remove whereas nitrates are less harmful and easily removed by regular water changes.

Removing particulate organic compounds and dissolved particles that are made of carbon and hydrogen and are too small to be caught in the filters is important.

Plants can use some of this matter and otherwise, it is mechanically removed by vacuuming gravel. Last, ensuring the correct minerals are present or added back with using RO water makes sure the fish in your fish tank have everything they need for good health.

How Often Should You Clean Your Fish Tank?

The short answer is regularly. It is best to set up a regular and consistent cleaning schedule so that your fish tank is kept in its best shape.

We recommend a staggered cleaning schedule that works out to a full cleaning once a month when a fish tank is new. During week one, you monitor water levels for Ph, temperature, and salinity and deal with immediate concerns by adjusting temperatures and using additives.

During week two, undergo gravel vacuuming and water changes. In the third week, change the filter mediums, and in the fourth week, rest.

If you repeat this pattern, you will have an easy to maintain routine and know how to clean a fish tank. Over time, if your fish tank is balanced, the demands for this type of cleaning will decrease.

How to Clean a Fish Tank: Step By Step

How to Clean a Fish Tank

Step One – Gather Your Supplies

You will need a few dedicated supplies on hand to clean your fish tank. Contaminants, such as household cleaning supplies and soap, can introduce harmful pollutants to your fish tank and put your fish at risk for illness or death.

Try to keep all of your fish tank cleaning supplies in one place and sealed to prevent harm.

Here is a list of supplies you may need:

  • Clean sponges
  • Clean towels and rags
  • A large bucket
  • Appropriately sized fishnets
  • Gravel vacuum or siphon
  • Filter mediums
  • Algae scrubbers
  • Prepared fresh water
  • Filter brushes
  • Water conditioners

Step Two – Preparation

Prepare as much freshwater as you plan to replace. Ensure this water is free from chemicals such as the chlorine commonly found in tap water. If you must use tap water, boil it and then let it sit for several hours before using.

Add water conditioners to reduce the chance of shock. Ensure your new water has the correct Ph levels, temperature, and salinity. Unplug all lights, pumps, and filters – anything that is powered.

Step Three – Decorations and Plants

Remove all decorations and artificial plants from the fish tank. Be careful to lift them slowly and gently so as not to disturb the gravel too much.

Wash them in warm water, using a clean scrub brush, if needed, to get off all algae and gunk. Rinse them well in warm water and set aside.

DO NOT USE SOAP. If decorations are stubborn or very dirty, you can soak them in a 10% bleach solution for 15 minutes and then scrub again.

Be sure to rinse well with prepared or fish tank water before returning to the fish tank. Do not remove live plants as you will disturb the root system and possibly kill the plants.

Step Four – Do Not Move Fish

When at all possible, leave your fish undisturbed while cleaning the fish tank around them. With a well-maintained fish tank, this is easy, and it will not cause any harm.

Fish will simply move to the other side of the tank to avoid you. Regular cleaning will not stir up enough toxins to worry about. Moving fish is stressful for them.

If you must move them because you are doing a completely fresh start or because your tank is so dirty the process may harm them, prepare a clean container with the original fish tank water and gently move them with an appropriately sized net.

Step Five – Vacuum Gravel

Gravel vacuums are an essential tool if your fish tank has a gravel base, which most do. You can purchase a vacuum for gravel at your fish tank supplier or local pet shop, or you can make your own homemade siphon.

A gravel vacuum pulls the debris out from under the gravel and carries it out of the fish tank while letting the heavier gravel fall to the ground.

You can regulate the flow by blocking the tube to slow it, and some gravel vacuums have automatic flow regulators.

(Note – Avoid gravel where fish eggs have been laid if you want the fish to hatch. Or, just delay your cleaning for the week it will take them to hatch.)

Step Six – Partial Water Removal

Partial water changes are made easy by siphoning through the gravel. You are removing excess accumulations of wastes while also removing water. You should remove about 25-35% of the fish tank water every month or 10-20% every two to three weeks.

If you regularly vacuum the gravel and do partial water changes, you will never need to remove all the water at once, which is preferred. A healthy microbiome is established when some water is left behind.

Step Seven – Remove Algae

Using a magnetic algae scrub, handheld algae scrub, or a scrubber designed to be used on the surface which your fish tank is composed of, remove all visible algae from the sides of the fish tank and any decorations you did not remove in preparation.

To ensure the scrubber you use will not scratch, it is best to buy a product made for cleaning a fish tank. DO NOT USE SOAP. For very stubborn gunk, you can use a razor blade on the glass and a plastic razor blade on acrylics.

(Note – If you incorporate a cleaning crew such as algae eating fish and snails, you will have far less, or no, algae to scrub at the fish tank cleaning time.)

Step Eight – Replace The Water

Replace the removed water with fresh, pre-treated water that has been brought to about the same temperature, Ph, and salinity as the old water.

Treat all water with a water conditioner, add salts to the correct salinity if you have saltwater tanks and if you use RO water, remember to replace needed minerals.

To make this step easier, we recommend you prepare the water the day before you plan to do your water change.

That ensures your prepared water is a similar temperature as the water in your fish tank and that chlorine found in tap water has been dissipated.

(Note – If you have moved your fish into a separate container, leave enough room for them and the water they are waiting in.)

Step Nine – Wipe the Outside Glass

Using just water and a clean towel, wipe up any spills and clean the exterior of the glass. Remember, do not use cleaners such as soap or window cleaners. It is just too dangerous for your fish.

If you must use something other than plain water, use a product specifically made for cleaning the outside of fish tanks or use a combination of vinegar and water.

Always rinse all surfaces really well with purified water or water taken from your fish tank. Even the smallest amount of cleaning products can be deadly.

Step Ten – Filter Cleaning

fish tank filter cleaning

It is best to follow the manufacturer’s instructions on how and when to clean your filters and change the filter mediums.

We recommend waiting a week to change the filter after your other cleaning as it will give your filter a chance to balance what you disturbed in the cleaning process.

Mechanical filters, such as sponges, ceramic, and filter fiber are removed and rinsed with the fish tank water. Return these to the water ASAP to keep the good bacteria alive and thriving.

Replace carbons, ion-exchangers, and ammonia absorbers as directed by the manufacturer or as dictated by your knowledge of water balances. Scrub the rest of the filter and all tubing using a filter brush.


Having a healthy ecosystem for captive fish means having a regular and consistent management of a fish tank and knowing how to clean a fish tank in a manner that promotes balance.

We recommend setting up a regular schedule, such as the rotating weekly schedule suggested in this article above so that cleaning your fish tank becomes a small regular task rather than a large overwhelming one.

Set up your fish tank with the right number of fish, the right fish, and helpers such as plants and algae consumers to make your work easier.

Over time, and with attention, your fish tank will become healthier and how to clean a fish tank will be something you can teach rather than learn.


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