How To Clean A Fish Tank

The environment in which your fish spends their time is understandably essential for their wellbeing. But fish tanks can suffer from various issues which affect their cleanliness and product build-up. Have a dirty tank and water on your hands and the welfare of your fish will suffer.

One clear way to know whether the tank needs cleaning is to simply have a look. If the glass is a little misty, and there is uneaten food or waste floating about in the water, you need to get your aquarium-appropriate plastic gloves on.

The good news is that it is a relatively easy job, but there is a certain knack for getting it right and ensuring that your fish spends as little time out of their tank as possible. Arm yourself with the best tools for the job and get reading…

What tools do I need to clean a fish tank?

Shoulder-length plastic gloves suitable for use in an aquarium are great for protecting your hands and skin, especially if it is sensitive or you have allergies. Keep some of these to hand at all times.

Grab an acrylic cleaning pad to ensure that the glass gets clean without the use of harsh chemicals, as you don’t want the water filled with these. These are also good for quick wipes. You can also get plastic scrapers to tackle tougher marks. Never use a normal sponge, and especially never use the one you use to clean other areas.

Fish Tank Cleaning Pad

Grab a bucket which can hold the amount of water you will be replacing. It is best to use the biggest bucket available, and only keep it for your fish water. You should use a manual siphon, not a battery, as you need full control over the motion and speed.

To get the gravel sparkling again, there are dedicated gravel washers out there. They can displace the gravel and suck up the dirt around it, without you having to remove any. Most have guards on them to stop fish and gravel being sucked up the pipe, which is vital especially if you have very small delicate animals.

You will also need to get the water to top up the tank ready. This could need treating, and you may want to add water conditioner too. Also, get a replacement filter or cartridge ready if this will need changing as well.

Although it isn’t recommended, if you really have to remove your fish, you will need a suitably sized net and somewhere to put them.

If you have a saltwater aquarium, you will need a few extra tools such as pH strips and salinity checkers.

Cleaning a fish tank: The process

Wipe it down

First of all, use your cleaning pad to remove any algae or marks stuck to the side of the glass. Start at the top and work as far down as you can go. This will drop down onto the gravel and sand area.

You should do this as smoothly as possible, without vigorous rubbing or motion. Plastic scrapers can clear tougher stains quickly.

Water change

How much water will need replacing? You should work this out officially by judging your nutrient (nitrate and phosphates) levels, but 20-40% per week is a good guide. For saltwater aquariums, this is only usually about 10%. It is worth noting that for freshwater tanks, a 10% change four times per week is not as good as a 40% change once per month.

Siphon out this old water, directing the old water into your bucket. They offer natural, slow movement so your fish don’t even realise some is disappearing.


There will be algae from the tank, along with waste and uneaten food. Don’t worry – you don’t have to pick every piece out one by one. You don’t even have to empty it all out. The gravel washer will do all of the cleaning. You should aim to clean at least 30% of this every month.

Keep the hose around one inch away from the gravel so you don’t disturb or remove any sand. You may wish to run your fingers through the sand every so often to remove any dirt which has worked its way right down.

Cleaning a Fish Tank


These can be magnets for algae. You can remove them or keep them in the tank, and use a cleaning pad or dedicated small toothbrush to displace this. Try not to use chemicals, but if they need to be soaked in a bucket in bleach then ensure all traces of this is removed before putting back into the tank, and that they are fully dry.

If the decorations are porous, such as wood or some stones, they will need to be dried for longer and treated.

Replace the water

Fresh, treated water at the same temperature as the aquarium should be used to top it up. Avoid overfilling it, and use a thermometer to check the temperature. You may even need to get it ready the night before if it needs to be dechlorinated. Your trusted siphon water remover will usually also be able to replace the water, again so the fish don’t realise it is happening.

Clean the exterior

Wipe down all of the outsides, including the tank, hood, stand and the lighting. Never spray cleaning fluid directly on to the glass, and there are special acrylic polishes out there.

Keep an eye

Is the water cloudy again after a few hours? There is something wrong, and the process will need to be repeated and the whole tank checked for faulty filters or something which has not been removed or disturbed by the cleaning.

This may mean the entire tank needs emptying, or you simply need to readjust the nutrient levels.

Cleaning saltwater aquariums

The general pattern above can be followed, although you will need to mix a saltwater solution ahead of time which is perfect for your fish. The water needs to be heated before adding salt, so read up about how best to do this.

You will also need to grab salinity probes, pH filters and check for salt creep. When the water is removed, it can leave behind a crusty residue which will need to be wiped away.

Removing fish from a tank

It is strongly recommended that you do not remove the fish every time you clean the tank, hence why you need so much dedicated equipment. If they are undisturbed, they can maintain a better temperature, aeration and overall conditions.

How to stop excess algae

Do your accessories need scrubbing every single week? You may have more algae build-up than is natural.

Light causes algae, from lamps to natural light. This is why your tank lights should be changed to dark mode during the night or when nobody is at home. You may also need to shield the tank from natural light occasionally, while still ensuring it gets enough for plant growth.

Talking of plants, these should help keep the water fresher for longer. You can also wipe away algae when it appears on the side of the tank or on the accessories, and add algae eaters to the water if appropriate.

You can lightly scrub any plants which are also seeing a build-up, but this should be rare.

Clean Fish Tank