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Tips on How Often To Change Aquarium Water | Tips And Guides

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You look into the aquarium and you see that the water is clean. But is it clean? Well, there are chances that after you stir up the substrate a bit you would find a huge amount of detritus that was settled in the bottom of the aquarium. So, what do you think, what is it from? It’s simple when you feed the fish, food particles fall to the bottom of the tank where they eventually decay. Whereas, the food that is consumed by the fish is eventually released back in the form of urine or feces, which adds up to the debris.

So, there are ample of questions and doubts related to the fish tank, how often to change Aquarium Water, it’s cleaning, etc. Let’s get to the bottom of these questions and find the most approximate solution or answer. Here we go.

How Often Should I change the Aquarium Water?


First and foremost concern and confusion of people who own fish aquarium is about the frequency of water changes. Well, to be honest, there are several aspects and deciding factors that tell the approximate aquarium water change frequency. For example, a smaller, heavily stocked tanks will require more frequent water changes than larger, sparsely stocked aquariums. The larger ones would be required once a week. Whereas, a lightly stocked would require water changes twice a week.

However, some people also think that adding water to the aquarium is the same as changing the water. Although, that is not the case as adding water does not remove any of the wastes. So, there’s no use skimping on the water changes because you’ve topped off the tank a couple of times. Now, there are a couple of important reasons for aquarium water change and why we are emphasizing the point of water change. Take a look at those reasons:
  1. Fish Become vulnerable to disease

    Apart from the junks that you can see other invisible byproducts build up in the form of nitrates and phosphates. These byproducts put stress on the fish and make them vulnerable to disease. Elevated nitrates retard the growth of young fish and can also interfere with normal reproduction in adult fish. They even promote the overgrowth of algae, leading to a slimy aquarium. Phosphates have an almost similar effect. Therefore, the best way to keep your fish healthy and aquarium clean is by changing the water at a proper interval. This is also how to change fish tank water in a small tank and not cause their life for this.

  2. Element and mineral reduction

    Waste is not the only reason why the water in an aquarium needs to be changed. Water chemistry also needs to be maintained to give the proper elements and mineral supply. The cleanliness of water brings in additional value to the water and keeps your fish healthy and the water chemistry stable. If the water in the tank is not replaced or filtered out on time, it will gradually result in the drop of water PH. These are the prerequisite of how often to change aquarium water.
reduces aquarium maintenance - great quality product
  • easy fix for cloudy aquarium water
  • essential biological cleaner for aquatic turtles
  • keeps your tank clean

First of all, what is pH? 


pH is a term that is used to describe the acidic and basic nature of a substance. The H refers to the number of hydrogen ions and hydroxide ions present in a liquid, such as your fish tank water. Higher is the number of hydrogen ions, the more basic the substance is. Whereas, the lower the number of hydrogen ions present, the more acidic the substance is. This somewhere or the other reduces the oxygen level in the water. These are some factors that you need to keep in mind while getting an insight about how often to change water in new fish tank.

Did You Know?

There is an aquarium aboard the International Space Station.

What would happen if the PH level of water in a fish tank drops?

Considering the above-stated results of lowered water PH level, it is very harmful to the fish in the tank and most probably would kill them. The water becomes toxic and there’s no oxygen to breathe. Furthermore, all of these situations will eventually result in the lack of trace minerals that will adversely affect the vigor and health of the fish. Therefore, you need to take care of the fact that the water is clean and is changed at a proper interval.

How Much Water Should I change in my Aquarium?

There are times when you do not have to completely change the entire water from the aquarium. But there are certain measurements that you should keep in mind while changing the water. You are supposed to change 10-15% of the water in an average aquarium. Change 20% of the water in a heavily stocked aquarium once a week, whereas you need to change 10-15% water in a lightly stocked aquarium biweekly.

So, these are the measurements and time duration chart that you must follow to keep the fish tank water healthy as well as fish in the tank healthy and alive. Other than that many other things require attention and care. For instance, the water filter in an aquarium is very important to keep the tank clean, sanitized and disease-free. So, let’s see some queries related to water fish tank filters like, when should you change the filter and many others.

Did You Know?

The world’s smallest aquarium is 30 x 24 x 14 mm and contains small baby fish that are replaced as soon as they grow.

What is an aquarium water filter?


An aquarium water filter removes the toxic buildup of ammonia and nitrates, cleans the debris in the water and aerates the water so your fish can breathe. With regular aquariums, you have to remove the fish whenever you are cleaning and then replace the water and return the fish.

Wherein, an aquarium with a water filter gives you ease with performing these tasks. They can easily be avoided. Well, now the question is if it is permanent? If now, how often does it have to be replaced? And why do we have to replace the water filter in a fish tank? There are many other answers to the questions related to water filters that like how often to change aquarium water, take a look:

Why Do We Have to Change The Water Filter?

Every mechanism requires regular maintenance and servicing to ensure proper functioning. It should always be working at its optimum potential to ensure that the water in the tank is continuously being cleaned. These are some basic factors that you should be aware of about changing aquarium water and replacing water filter.

Although it also depends on the type of filter you are using because there are filters that require less changing period and some require more changing periods in comparison to others. Changing filters too frequently also isn’t as good as it can be very disastrous. This can certainly wash away beneficial accumulated bacteria.

Therefore, to balance out the filter change, you can invest in good sand or gravel containing pre-added bacteria. This is also how to change fish tank water without killing fish. There are numerous filter types that have variation in the time slot of filter reinstallation and maintenance.

Types of fish tank filters: 

  • Mechanical Filters

  • Chemical Filters

  • Biological Filters

  • Canister Filters

  • Box Filters
quiet filter - suitable for aquariums up to 40-gallons
  • awesome for turtle tanks
  • great for pet water fountains
  • perfect for low flow fish tank

Did You Know?

Lights should only be on 6 to 8 hours a day and are only essential if growing live plants.

When to change my water filter? 

Moving on, people generally have this issue that how often should I change my fish tank filter. Well, there is a proper time interval for water filter replacement or reinstallation. Although that also depends on the type of filter that you are using. You need to make sure that you are doing it at a proper interval so that you do not let the water get toxic.

Yet, we can give you a generalized insight of when exactly you should change the fish tank water filter. Well, in some cases you just need to do proper cleaning every month or you also might have to replace the filter every 2 months.

Theres a difference between adding water and changing water

People usually misunderstand the fact about water adding and changing. What they think that both of them are the same thing and that through this they are keeping the aquarium clean, which is not right. So, the difference between adding water and changing water is that when you keep adding water it doesn’t clean the aquarium. Whereas, when you change the water, you do a complete tank cleaning and water restoring. So, when people want to know how often to change the water in the new fish tank, this is how often.

What kind of water test do i need to conduct for my aquarium?

As complicated as it might sound testing the quality of aquarium water is very easy to do. All you need to do is get a store-bought water testing kit and use it to measure the important parameters in your aquarium water, such as pH, alkalinity, ammonia, nitrite, and nitrate. This is how you can view the results by matching it to the color chart.

Video Introduction


​Bringing this entire article to a conclusion, you might have had quite a good insight into the fish tank, water changes, testing, and a lot of other things. There are certain points that you need to take care of as mentioned. Knowing how often to change aquarium water and many related questions can help you in keeping your aquarium well-sanitized so that your fish have a healthy life.

Along with it, it’s also helpful in keeping it beautiful and long-lasting. So, make sure that you are looking into every aspect of keeping your aquarium clean and your fish healthy. Also, make sure that you are using verified and registered tools or equipment as they also decide the quality keeping of your aquarium.

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