Goldfish Tank Cleaning

Goldfish are hardy creatures that are pretty resilient and adaptable when it comes to their living environment. 

However, goldfish are very dirty fish that produce lots of waste, so you must be prepared to spend time cleaning and maintaining your goldfish tank if your pets are to remain healthy and thriving.

Read this article to learn everything you need to know about goldfish tank cleaning.

How often should a goldfish tank be cleaned?

Once your goldfish tank is set up and fully cycled, you’ll need to clean it once a week.

As mentioned above, goldfish are dirty fish, and you must remove the mess they make to keep the tank environment clean and hygienic. 

There’s no need to take down the tank completely, as that would remove most of the beneficial bacteria crucial to maintaining a healthy environment for the fish.

The exceptions to that rule are tanks where an undergravel filter system is used. Undergravel filter plates are placed directly on the floor of the aquarium underneath the substrate. 

Over time, fish waste and general detritus accumulate under the filter plate. So, you’ll need to remove all the water, plants, substrate, and decorations so that you can clean thoroughly underneath the filter plate. 

For that reason, we don’t recommend undergravel filters for goldfish tanks. In my experience, an external canister filter or HOB (Hang On Back) filtration system is the best choice.

How to clean a goldfish tank

You’ll need to clean your goldfish tank every week to keep the environment safe and healthy for your pets.

Here’s how to do it:

1. Assemble What You Need

Start by assembling everything you need for cleaning your tank, including:

  • Aquarium vacuum cleaner
  • Bucket
  • Dechlorinator
  • Algae scraper
  • Replacement filter media (if required)
  • Filter system brushes

Unless you need to take your tank down completely, you won’t need to remove your goldfish from the tank while you’re cleaning it. 

Don’t be surprised if your fish come to investigate your fingers while you’re working; just be careful not to suck the fish into the aquarium vacuum cleaner accidentally!

2. Clean Filter Pump and Filter Media

Start by turning off your filter pump and lighting unit.

We recommend that you clean the filter pump every two weeks in a goldfish tank, as these are filthy fish! 

The filter media will need rinsing in tank water every few weeks to prevent it from becoming clogged with sludge, which would stop the water from flowing through the filter system and prevent the filter from working efficiently.

Disassemble the filter pump and use your brushes to remove algae and sludge. Rinse or replace the filter media as required.

Reassemble the filter pump but don’t switch it back on yet when you’re done.

3. Vacuum Your Fish Tank

Now, use an aquarium vacuum cleaner to eliminate any accumulations of organic waste from around plant bases under internal filter boxes and decorations. 

Work the vacuum cleaner deep down into the gravel and into the tank corners to remove as much detritus as you can.

4. Change 30% Of The Water

You need to change around 30% of the tank water every week to dilute nitrates and keep the environment safe and healthy for the fish. 

You can use tap water to top up your fish tank, but you must treat the water with a dechlorinator product before you add it to your aquarium. 

The chlorine and chloramine that tap water contains are extremely harmful to fish and can cause chemical burns to the creatures’ delicate gill tissue. Read the manufacturer’s instructions carefully so that you add the correct amount of treatment to the water.

Check the water temperature with your aquarium thermometer before adding the water to your fish tank. Goldfish are pretty hardy creatures, but you don’t want to have the water too hot, as that could cause temperature shock, which could harm your fish.

5. Trim Plants

If you have live plants in your fish tank, you’ll need to trim off any dead leaves and damaged stems. Thin out plants that are becoming overgrown using aquascaping scissors.

6. Remove Algae From The Viewing Panes

To prevent algae from becoming a slimy, green problem, use an algae scraper to remove any colonies of algae from your viewing panes. 

You might want to leave some algae growing on stones and decorations, as the goldfish will graze on it throughout the day, and the juicy green stuff provides a nutritious addition to the fish’s diet.

Sometimes, colonies of algae grow on the tank lid directly beneath the lights. Use your scraper or a sponge to remove the plants if you find any.

7. Finish Off

Reconnect your filter system and lighting unit, and switch them on.

Check that everything is working correctly, and adjust the filter outflow to buffer the current if necessary.

Where do you put your goldfish when cleaning the tank?

Netting your goldfish is highly stressful for them. Stress compromises the fish’s immune system, leaving the animal vulnerable to attack by parasites and bacterial diseases. 

So, if you can possibly avoid doing so, don’t remove your goldfish from their tank while you’re cleaning it.

A goldfish aquarium should be plenty large enough for your fish to remain in situ while you’re changing 30% of the water, vacuuming the tank, and carrying out your other routine maintenance tasks. 

If you do need to remove your fish from their tank, put them in a large bucket half full of tank water. Cover the bucket to reduce stress, and don’t feed the fish while they are in there to prevent excess waste from contaminating the water. 

Don’t leave the fish in the bucket for more than an hour at the most before replacing them in their clean tank.

How often should I change my goldfish tank water?

You should change 30% of your goldfish tank water every week.

However, if the nitrate levels in the water are higher than 30ppm, you might need to carry out small water changes every day until the levels fall.

How do I change my goldfish tank water?

The most efficient and easiest way to change your goldfish tank water is to use an aquarium vacuum cleaner.

An aquarium vacuum cleaner is basically a rigid plastic tube of around 2 inches in diameter that’s fixed to a length of plastic hose.

Some designs have a valve system inside to control the water flow and prevent blockages. Other vacuums can be hooked up to your kitchen sink for syphoning, but most devices work with the assistance of gravity. 

Vacuum cleaners can either be manual or use an air-filled bladder that must be pumped a few times to start the syphoning process.

How does an aquarium vacuum cleaner work?

Fish tank vacuum cleaners work by using gravity to syphon water and waste from the substrate in your goldfish tank. 

The vacuum agitates the substrate inside a column of rotating water, dislodging debris from the gravel and syphoning off the dirty water.

How do I use an aquarium vacuum?

You need your aquarium vacuum cleaner and a large bucket to collect the syphoned dirty water. Place the bucket on the floor below the water level in your goldfish tank so that the syphoning process works properly.

  • Put the plastic part of the device into the fish tank and hang the aquarium hose over the side of the aquarium so that it drains into the bucket.
  • Start the syphon by dipping the vacuum head into the fish tank so that it fills with water. Once the vacuum head is full, take it out of the aquarium and allow the water to drain down through the hose and into your bucket.
  • Before the vacuum head empties completely, put it back into the water. Air gathers inside the hose when the head is underwater, dragging water through the vacuum device and starting the syphoning process.
  • Push the vacuum down into the substrate and move the gravel around gently. Light waste fragments, such as fish waste, uneaten food, and general detritus will be sucked into the vacuum.
  • The waste passes down the hose and into the bucket in just a few seconds.
  • As you work, concentrate on the areas in the tank corners, under rocks and decorations, and around plant bases where most of the detritus collects.
  • When the job is done, rinse your vacuum in warm water, and store it somewhere dark and cool until next time.

Types of aquarium vacuum cleaners

There are two primary versions of aquarium vacuum cleaners, each having its own pros and cons:

Electric Gravel Cleaners

Electric aquarium vacuum cleaners pump tank water through the device, snaring any debris in a filter and returning clean water to the aquarium.

The primary advantage of using an electric gravel cleaner is that you can give your goldfish tank a really thorough deep clean without being restricted by the amount of water the tank contains. 

The main downsides of this type of cleaner are that they are expensive and not ideal for a small fish tank. These cleaners need a minimum tank depth to work properly, and the suction they provide is rather weak.

Manual Syphon Gravel Cleaners

Manual syphon aquarium cleaners are by far the most popular variety of fish tank vacuum devices. These syphon-style cleaners consist of a length of plastic hose and a hollow tube cleaner.

These devices come in a range of sizes to suit most goldfish tanks, are easy to use, and are cheap to buy. The main downside to this style of cleaner is that you need to remove water from the tank to clean the gravel.

Safely replacing water in your fish tank

Water dechlorinator

When it comes to replacing the water in your fish tank, you must NOT use untreated tap water

Tap water contains chlorine and or chloramine. Those chemicals are added to your domestic water supply by water treatment companies to kill bacteria and make the water safe for you to drink, wash in, and use for cooking. 

However, both of those chemicals are highly poisonous to your goldfish.

To make the water safe, you must add a dechlorinator treatment. These treatments immediately neutralise chlorine, making the water safe for your fish.

When adding clean water to your aquarium, check that it’s the same temperature as the water in your fish tank to prevent temperature shock. Pour the water slowly into the tank so that you don’t disturb the substrate or frighten your goldfish.

How to safely clean fish tank decorations

The decorations in your goldfish tank can get dirty over time, and they can also accumulate deposits of algae. 

Although your goldfish enjoy grazing on lush green algae, a coating of slimy plants covering your ornaments can make the tank look unsightly, so you might want to clean your decorations from time to time.

Of course, you can’t use chemical cleaners near your fish tank and its contents, as you might accidentally poison your goldfish! 

Instead, you can safely use ordinary white vinegar that you’ll most likely already have on hand in your kitchen.

Using white vinegar to clean your tank is a very cheap and amazingly effective way to remove stubborn water stains and hard algae from your viewing panes, decorations, and even living plants.

Green Spot Algae

Most of the lush, green algae you’ll see in your goldfish tank is relatively easy to remove. 

All you need to do is gently rub the algae with a sponge. However, Green Spot Algae are tough to shift since it forms rock-hard spots that can blemish your ornaments, aquarium glass, and even your living plants.

Hard Water Stains

Some areas have what’s called “hard water.” Hard water contains high levels of mineral deposits (calcium). 

As the water in your fish tank evaporates, it leaves behind those minerals as a white residue, typically on your glass or filter equipment.

What equipment do I need to clean fish tank decorations?

Before you get started on your cleaning job, gather together the following items:

  • White vinegar
  • Tap water
  • Clean sponges
  • An old toothbrush

How to clean your plants using white vinegar

Here’s how to get rid of accumulations of algae on your living plants’ leaves:

  • Make up a solution of white vinegar and tap water in 1 part water to 1 part vinegar. Allow the plants to soak in the solution for five minutes.
  • Rinse the plants under cool running water to eliminate loosened algae and the vinegar solution. 

Replace the clean plants in your goldfish tank.

How to clean goldfish tank decorations in white vinegar

  • Add a solution of water and white vinegar in the ratio of 1 part tap water to 1 part vinegar to a clean bucket.
  • Allow the decorations to soak in the solution for ten minutes or longer if badly stained.
  • Rinse the decorations in clean water to get rid of dirt and the vinegar solution.
  • Now, use an old toothbrush to scrub each item to remove any remaining stains. If necessary, dip the brush in undiluted vinegar and concentrate on any stubborn areas of staining.


You can also use a white vinegar solution to tackle stains on your fish tank glass, as the solution is harmless to your fish.

Final Thoughts

Did you enjoy our guide to goldfish tank cleaning? If you found the information helpful, please share the article!

You’ll need to devote some time every week to change 30% of the water in your goldfish tank. At the same time, use an aquarium vacuum cleaner to remove fish waste and other organic debris from the tank so that it doesn’t decompose and pollute the water. 

Remove algae from the aquarium viewing panes, and use a solution of white vinegar and water to clean living plants and tank decorations.

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