How To Clean a Dirty Aquarium

It generally takes about 30 minutes to an hour to clean and maintain a fresh water fish tank, depending on the size.


The cleaning of the tank can be divided into 2 parts.

1. Cleaning your goldfish aquarium filters every 2 to 3 weeks

2. Cleaning the tank once a week, on the same day.

step by step instructions for cleaning a goldfish tank

use a gravel cleaner to save time and effort

Step 1 : This is what you’ll need

  1. 1 x 5 gallon bucket that has never been used or hasn’t had any soaps or chemicals in it
  2. A gravel cleaner or a hose
  3. Depending on your tank (ie whether it’s salt water or not) – water conditioner/ 1 bag of synthetic or natural sea salt

Step 2 : Start the cleaning process of the fish tank

If you’ve got a heater: You’ll need to remove the heater. Make sure the heater has been unplugged for at least 20 minutes before attempting to remove it as it shouldn’t be taken out of the water while it’s still very hot. This could cause the glass of the tank to crack or even shatter. Leaving the heater in the water helps the heater to cool down so that it can be safely removed.


A note of caution: Never put your hand inside the fish tank before making sure the heater is turned off and unplugged from the electrical outlet. Even a tiny fracture in the heater could give you an electric shock that could be fatal.

Step 3 : Remove aquarium accessories and clean the gravel

You’ll need to take out decorations or aquarium accessories you have in the tank so that only the gravel at the bottom of the tank is left. This lets you clean the areas that were occupied by the decorations.


If you don’t have gravel cleaner then you’ll have to clean it the old-fashioned way by rolling up your sleeves and getting your hands wet.


Stir up the gravel to loosen the dirt that’s accumulated so the dirt can be removed from the water. However, don’t throw out the water because it will be used to clean the filters.

If you do have a gravel cleaner, insert the plastic tube into the gravel until it touches the bottom of the tank then start siphoning the dirt into the bucket. Move the tube every couple of seconds an inch or two until all the gravel has been cleaned or if about 15% of the water has been removed from the tank.


Step 4 : Clean the aquarium filters

Now you can start cleaning the aquarium filters. The filters are used to grow bacteria which help break down nitrates in the water that come from fish waste and uneaten food. The bacteria are goldfish tank friendly so you need to make sure they aren’t killed or removed from the tank.


Clean the filter materials and sponges by using the bucket of dirty water taken from the fish tank. Give the sponge a few squeezes in the bucket of water and then reassemble the aquarium filters and put them back in the tank.

Step  5 : Add water

Don’t forget the water conditioner!

Very important: Don’t expect fish to tolerate straight tap water well. This is because tap water is heavily treated with harsh chemicals like chlorine to make it safe for human consumption. This can be fatal for our fish to swim through.


Use a water conditioner for fish, like Nutrafin aqua plus, to treat the aquarium water.

For Tropical Salt Water Tanks:

You must add sea salt to the tank before adding water. Adding salt to the tank is intended to replicate the natural habitat of the fish.


Use an ocean sea salt for marine aquariums that’s nitrate and phosphate free. Check price on amazon for ocean sea salt.


For every 50 gallons of water add 1 cup of sea salt. Once that’s done you can then add water. The water added must be roughly the same as the temperature of the water in the tank, at least within 1 or 2 degrees.


A drastic and sudden change in the tank’s water temperature can weaken the immune system of the fish leaving them susceptible to various fish diseases. Or worse, it could send the fish into shock and kill them.


To achieve the correct temperature, try filling the bucket with hot water and then check the temperature frequently until it matches the temperature of the water in the fish tank. Slowly add the water to the tank, and then start the filters and the heater.

salt for changing water in fish tanks

Aquarium filters can be cleaned once or twice a month but the tank water needs to be cleaned on the same day every week.

This is a vital part of aquarium maintenance and keeping your goldfish healthy.

Water change tutorial video