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How To Change Your Aquarium Water? (The Complete Care Guide)

Air is to us as water is to fish. Water is what keeps a fish alive. But ironically, water can also really harm your fish.

Don’t be shocked when I talk about dangers as dirty water will always give rise to infections that will ultimately harm your fish.

The truth is, even crystal clear water can have several types of diseases which can affect your fish — it could be like a silent killer.

A lot of factors will determine the right quality of water where the fish can have a healthy environment.

People often commit the mistake of not changing water or not removing the organic debris from the aquarium.

This is not all; at times they forget the importance of the test kits that helps in determining the right pH level of the water.

So, when you tend to forget these small things, you are allowing something big to happen.

Fish are fragile species and can only survive in a clean environment. A crowded aquarium makes it hard for them to survive because it can give rise to a variety of disease which would be a threat to your fish.

Let’s get into some important chemical reactions:

Here, I would like to talk about some basic things that go on in an aquarium. These are fundamental stuff but you really need to understand them to be a successful fish keeper.


  • The remains of food, along with fish waste, in the aquarium get infested by bacteria. They get converted into ammonia and then to nitrite and finally nitrate. Although nitrate in low concentrations may not be a toxic form of nitrogen, it threatens the aquarium if left unchecked. It gradually drops the pH level and lowers the alkalinity of water.
  • There are other chemicals like pheromones and phosphates that play an active role in deteriorating the health of the fish.
  • Dirty water definitely stresses the fish and acts as a catalyst to welcome the infections.
  • The most common type of infections that fish encounter is parasitic and fungus problems.
  • Gills can be the favorite invading ground for most of the bacterial infections. When gills get rotten or form spots because of the infections, it is a clear symbol that your fish won’t survive for much longer.
  • Cloudy or dirty water will definitely contain lower levels of oxygen and as a result the fish gasp for breath. In this scenario, they are usually seen swimming near the surface of the water.

What is the right way to change water?

The above points clearly illustrate the need to change water often in your tank. However, there is no set of rules regarding the right way to change the water.

I have seen people changing water every alternate day, once a week, once every 15 days (all depending on the size of the tank, number of fish you have and how much water you take out at a time)

Now the question is; in what proportion should you change the water?

First of all, what you need to see here is the level of nitrate. Your main aim should be to keep the nitrate level as low as possible.

As I have already mentioned above; a little amount nitrate may not be very toxic by itself, but a small change in its level in water can create havoc. Keep the ph level less than 40ppm, always.

Secondly, do not commit the mistake of changing the whole water of the aquarium. It will stress the fish at once.

Start with changing 20-30 percent of water every week. Alternatively, you may also change 50 percent of water every two weeks.

The choice is yours. Remember never to overcrowd an aquarium. There should not be more than 3-4 fish in the tank (obviously, this depends on a tank size and the size of the fish).

If you add more fish, the water chemistry will change more quickly.

Cleaning is very important !

  • Sterilize the gravels and the rocks once in every two weeks. This will give you an assurance that no bacteria or infection will intrude the aquarium.
  • If you have seen the formation of algae on the glass or on any part of the decorations, simply scrape it using algae scrubber pad. This is important as you don’t want your fish to get ill. A solution of chlorine bleach and water can do well in removing the excess algae. All you have to do is just dip the cleaning materials in this solution.
  • Pre-measure things like buffers, ammonia neutralizer, dechlorinator, etc. to go with the amount of water you want to change. You take the help of a bucket to do this task.

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2 thoughts on “How To Change Your Aquarium Water? (The Complete Care Guide)

  1. […] is crucial to maintain a healthy, clean environment for fish. Water needs to be changed on a regular basis depending on how many fish you have and how big the tank […]

  2. […] is crucial to maintain a healthy, clean environment for fish. Water needs to be changed on a regular basis depending on how many fish you have and how big the tank […]

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