How To Use Water Conditioner For Fish Tank Safely

Estimated read time 22 min read

In this article, you’ll learn the right way to use an aquarium water conditioner.

We’ll also answer a few common questions like:

  • Why you need it?
  • How much to use?
  • Is it safe for your fish?
  • What’s in aquarium water conditioners?

Lastly, we’ll finish it all with our recommendations for the best water conditioners.

That said if you’re in a rush?

We decided to take a closer look at some of the best aquarium water conditioners available to find the best brands out there.

Of the many brands we use, these are the top 3 aquarium water conditioners to buy in 2021:

  1. Seachem Prime
  2. API Water Conditioner
  3. Fluval Water Conditioner

Let’s begin!

Table of Contents

Do You Need Water Conditioner For Your Fish Tank?

In most cases, you will need to add some water conditioner to your tap water.

Water conditioners ensure that the water in your aquarium is safe before adding fish.

It detoxifies the water and makes it biologically stable.

However, some people overlook adding water conditioners which can potentially harm your fish.

If you want your fish to thrive, stay healthy, and active, you most definitely need to use a water conditioner.

Why Do You Need It?

Tap water isn’t pure.

Chloramines and chlorine are added to the water at water treatment plants, which isn’t safe for your fish.

These oxidizers kill bacteria present in water, both harmful and beneficial ones.

Tap water can also contain parasites, dissolved chemicals, and other impurities that may affect your fish’s health.

These impurities aren’t uncommon, which is why it’s super important to use a water conditioner to make the tap water safe for fish.

But what if you don’t want to use chemicals?

Are there other ways to may your tap water safe?

Can You Make Tap Water Safe Without Using Water Conditioner

Yes. There are several alternative methods you can use to condition tap water without using a water conditioner.

Although using a water conditioner is the easiest way to condition the water for your fish, here are a few other techniques that can help.

Reverse Osmosis

Reverse osmosis is one of the best non-chemical methods of making water in your fish tank suitable and safe for your fish.

Reverse osmosis can remove as much as 99% of the dissolved particles in water.

Reverse osmosis also removes harmful chemicals like chlorine and fluoride from tap water.

This method purifies water to the extent that it becomes safe for human consumption as well.

Some local fish stores sell R.O water in 5-10 gallon amounts that you can purchase if you don’t have access to a reverse osmosis system – not sure who would, in all honesty.

Electromagnetic Water Treatment

Electromagnetic water treatment is a non-chemical technique of softening hard water considerably.

It does so by moving the water through a magnetic field.

Some homes have water softening systems that may use this technology to look into if you don’t want to use water conditioners.

Template-Assisted Crystallization

This is another alternative you can use to purify the water in your fish tank.

It converts soluble magnesium and calcium ions present in the water into insoluble and harmless crystals that don’t affect the well-being of your fish in your fish tank.

I wouldn’t know where to start with this method, but I know it’s out there.

Let Your Tap Water Sit

Lastly, and the ultimate for the lazy at heart.

You can just let your tap water sit for 26 to 28 hours before using it.

Also, aerating can help speed up by moving the water around and oxygenating the water.

In all honesty, all of the alternatives above aren’t as easy as adding a few drops of liquid.

Next, let’s look at what water conditioners do after you add them to your water.

What Does Water Conditioner Do For Your Fish Tank?

Water conditioners are liquid chemicals that neutralize chlorine, chloramines, and other harmful components present in tap water to make it safe for fish.

Chlorine and chloramines, in particular, can be fatal for your fish if not appropriately treated.

Water conditioners neutralize chlorine and chloramines present in the water by forming ionic bonds that render the chlorine content harmless.

A water conditioner behaves like a magnet that pulls all the chlorine molecules away from your fish and prevents it from entering your fish’s body through its gills.

Tap water also contains chloramines.

A water conditioner splits the bond between chlorine and ammonia in the chloramine molecules.

Water conditioners may either be specific for chlorines, chloramines, or both.

Using a water conditioner that deals with both these oxidizers are your best bet at making the conditions of your fish tank ideal for your fish.

Are Water Conditioners Safe For Fish

Water conditioners are safe for fish.

However, you do need to ensure that you follow the dosage guidelines provided by each manufacturer.

We provided a dosage chart for some of the most popular water conditions later in the article;

That said, water conditioners that do not remove chloramines can cause harm to your fish.

These water conditioners only treat the chlorine content of chloramines and leave free ammonia in the water that is also extremely dangerous, even fatal for your fish.

This is why water conditioners like Seachem Prime also help detoxify ammonia.

Wondering if Seachem Prime is the ultimate water conditioning solution for your aquarium? Our in-depth analysis of Is Seachem Prime the Ultimate Solution for Water Conditioning? will provide you with all the answers you seek. Click here to learn more about this exceptional product and make an informed decision.

Another instance where a water conditioner might be unsafe for fish is when it contains too many ingredients.

Over time, these ingredients build up in the tank water and make the environment for your fish unhealthy, even dangerous at times.

This is why your weekly water changes are so important.

While we are talking about ingredients, let’s look at what is typically found in water conditioners.

Video: The Truth About Dechlorinators

Here is an awesome video from AquariumCo-Op where Cory explains some of the cons of using water conditioners and some important things you should know about before using them.

Typical Aquarium Water Conditioner Ingredients

A water conditioner works through a series of Redox (Reduction/ Oxidation) reactions.

The active ingredient of aquarium water conditioners is sodium thiosulfate, a powerful reducer that reduces harmful oxidizers present in aquarium water.

Other ingredients of aquarium water conditioner include Vitamin C, which is also a strong reducing agent.

Vitamin C isn’t as powerful as sodium thiosulfate but can break down the harmful chlorine present in the water.

A few other common ingredients are

  • Aloe vera
  • EDTA tetrasodium salt

How to Use Water Conditioner (Instructions)

Water conditioners are deemed safe for fish, and there’s no need to remove your fish from the tank before adding the product to the water.

But always;

  • Read the instructions before adding the water conditioner to your fish tank.
  • Pour the suggested amount of water conditioner directly into your fish tank.
  • If you remove your fish before adding the water conditioner, leave it for 15 minutes to allow the product to spread evenly across the water before you add your fish back in.

Suppose you’re concerned that pouring the product directly into the water can be harmful to your fish.

In that case, you can dissolve the suggested quantity in a small amount of water to dilute the product before adding it to your fish tank.

Although it’s unnecessary, you can take any precautions that you feel you should ensure your fish are safe.

When Should You Add Water Conditioner To Your Tank

You should add a water conditioner every time you change the water or set up a new aquarium.

Even if you aren’t changing the water completely and are only topping it off, you should make it a practice to add a few drops of water conditioner to it.

You should also add a water conditioner to your fish tank following a partial water change.

A water conditioner must be added with each water change.

How Often Should You Use A Water Conditioner

The frequency at which you should use a water conditioner depends on the frequency at which you’re changing your fish tank’s water.

You should add a water conditioner every time you change the water, whether it’s weekly, bi-weekly, or monthly.

Adding a water conditioner to your fish tank when you aren’t changing the water isn’t recommended. It might lead to the chemicals getting concentrated, which can affect your fish adversely.

How Long Should You Let the Water Conditioner Sit Before Adding Your Fish

If you want to wait, 15 minutes is sufficient to ensure the water conditioner is dissolved in the water evenly.

However, it’s not a necessity. Water conditioners are considered safe for fish.

You can add the product directly into the water containing fish. If you have removed your fish for changing water, you can add your fish right after adding the water conditioner.

Related: Why wait 24 hours before adding fish to your tank.

Can You Add Water Conditioner With Your Fish In The Tank

Of course, you can add a water conditioner with your fish in the tank as these products are considered safe for your fish.

However, to make sure your fish doesn’t consume the concentrated product before it’s dissolved, you can lure your fish to the opposite side of the tank with some food or treats.

How Much Water Conditioner Is Needed per Gallon

The amount of water conditioner suitable per gallon varies from product to product.

If you’re using a concentrated water conditioner, you’ll need to add a lesser quantity per gallon of water than a diluted water conditioner.

Below you’ll find a dosing chart for some of the most popular water conditioners available.

That said, always refer to the product manual for instructions.

Aquarium Water Conditioner Dosing Chart

GallonsSeachem PrimeAPIFluvalTetra Aqua SafeAqueon

Can You Overdose Water Conditioner

The safety margin for water conditioners is usually high, usually several times the recommended dose, so even if you overdose, your fish should be okay.

However, that doesn’t mean you can’t overdose to the extent that might affect your fish.

If you feel you’ve added too much water conditioner, do an immediate water change to dilute the concentration.

How Long Does Water Conditioner Take To Work

It usually takes approximately 15 minutes for the water conditioner to work in a pre-established tank.

What Are the Best Aquarium Water Conditioners For Your Fish Tank

There are many to choose from, and all work very well. That said, we listed some of the top water conditioners below to help you choose the one that suits your requirements and budget the best.

Seachem Prime

Seachem Prime Water Conditioner is one of the best water conditioners for your fish tank.

It is suitable for use with every water change and also when you’re setting up a new aquarium.

What makes the Seachem Prime the best water conditioner is that it can be used for freshwater and saltwater.

Seachem Prime is five times stronger than other water conditioners.

It detoxifies nitrate, nitrite, and ammonia and removes chloramines, chlorine, and heavy metals from tap water, making it safe for your fish.

It’s an ideal water conditioner that you can use with every water change and can also be used during tank cycling to address nitrites and ammonia toxicity.


  • It detoxifies water in your fish tank and removes chlorine and chloramines efficiently
  • It’s versatile and can be used for both fresh and saltwater.
  • It addresses heavy metals in tap water and removes them.
  • It can detoxify nitrogen compounds as well, including nitrates and nitrites.
  • It doesn’t change the pH of the water in your fish tank.
  • It doesn’t put fish under stress.


  • It has a powerful characteristic sulfur odor.
  • It gives false ammonia readings sometimes.
  • It’s hazardous for humans.

API Tap Water Conditioner

API Tap Water Conditioner works great for detoxifying water of chlorine and heavy metals.

What makes the API Tap Water Conditioner an excellent water conditioner is its value for money.

It offers excellent value per gallon.

It’s highly concentrated has the highest concentration of dechlorinating agent compared to all other fish tank water conditioners.

Only a tiny quantity of this conditioner can condition your whole aquarium, hence the excellent value per gallon.

It neutralizes other chemicals present in your fish tank that may affect your fish’s health, irritate your fish tissues, and lead to fish death.


  • It’s highly concentrated, and hence, only a tiny amount is used.
  • It offers the best value per gallon.
  • It detoxifies water of chlorine and heavy metals.
  • It can neutralize other harmful chemicals that can affect your fish’s health adversely.


  • It’s not suitable for small tanks due to the high concentration.
  • It doesn’t detoxify chloramines, leading to the accumulation of ammonia content in your fish tank that can be fatal for your fish.
  • You’ll have to bear the additional cost of a new product to remove ammonia.

Fluval Aquarium Water Conditioner

Fluval Aqua Plus Aquarium Water Conditioner is another excellent choice for water conditioners for your fish tank.

Fluval water conditioner removes harmful chemicals and metals from the water efficiently and quickly.

It’s a complete water conditioner which means it removes chlorine, chloramines, and heavy metals.

Not only does the Fluval Aqua Plus remove harmful chemicals from the water, but it also offers your fish the protection they need to stay healthy.

It promotes healing in fish that are injured or wounded, reduces fish stress considerably, and supports healthy fin growth.



  • It’s not very concentrated, which means you’ll have to use more of the product to get the desired results.
  • Since it’s used in more significant quantities, it doesn’t offer the best value for money per gallon.
  • Treatment of water using the Fluval Aqua Plus will cost you more.

Tetra Easy Balance Aquarium Water Conditioner

The Tetra Easy Balance Aquarium Water Conditioner prevents the occurrence of several conditions that are harmful to your fish.

It reduces the water’s alkalinity and lowers the pH to establish ideal conditions for your fish.

Tetra Easy Balance reduces the amount of phosphate and nitrates in the water from fish waste and can cause fish stress if not removed.

Tetra Easy Balance not only detoxifies the water in your fish tank but also nourishes it.

It contains vitamins, minerals, and electrolytes that improve water quality and make the tank environment healthier for your fish.

With this water conditioner from Tetra, your fish will thrive!


  • It efficiently removes nitrates and phosphates from the water,
  • It reduces fish stress.
  • It reduces the alkalinity of the water and maintains an optimal, ideal pH.
  • It contains vitamins, minerals, and electrolytes that promote fish health.


  • It’s not suitable for fish tanks that aren’t sufficiently oxygenated.
  • It’s not a complete water conditioner for tap water. It doesn’t remove chlorine and chloramines.
  • You’ll have to invest in another product that can effectively remove chlorine and chloramines from your fish tank.
  • It’s not highly concentrated; hence you’ll have to use more of the product.

Aqueon Water Conditioner

Last on our list is Aqueon Water Conditioner.

It neutralizes chlorine, chloramines, heavy metals and also removes fish waste and heavy metals.

A bonus of the Aqueon Water Conditioner is that it also detoxifies ammonia.

Another benefit of using the Aqueon Water Conditioner is that it promotes the restoration of the natural mucous coat on your fish body, usually lost when transferring fish.

This helps protect your fish from getting injured and also promotes the healing of wounded fish.

The Aqueon Water Conditioner is an excellent fish stress reducer. It promotes the overall well-being and health of your fish.

What makes this water conditioner so popular is its price. It’s an excellent product for the price.


  • It’s a complete water conditioner that detoxifies tap water efficiently.
  • It removes chlorine, chloramines, heavy metals, fish waste, and ammonia.
  • It promotes the restoration of mucous membranes on a fish’s body.
  • It protects fish from injuries.
  • It promotes wound healing in fish.
  • It offers an excellent value for money.
  • It reduces fish stress significantly.


  • It’s not very concentrated.
  • The Aqueon Water Conditioner is used in greater quantities which puts a question mark on the cost-effectiveness of this product.
  • Poor value per gallon.

User Guide

Aquarium enthusiasts understand that ensuring the well-being of their aquatic pets starts with providing a safe and conducive environment. Water conditioners play a crucial role in this process, as they can make tap water safe for fish by neutralizing harmful elements such as chlorine and chloramine. In this comprehensive guide, we’ll delve into various aspects of using aquarium water conditioner to maintain a healthy environment for your aquatic animals.

Determining the Right Amount of Water Conditioner

Calculating for Gallons of Water

One of the first steps in using water conditioner is understanding the appropriate dosage based on the number of gallons of water in your aquarium or during a water change. Overusing or underusing conditioner can impact your fish’s health and the aquarium’s water quality.

Small Amounts for New Tanks

For those with new tanks, it’s essential to exercise caution and use smaller amounts of conditioner initially. New tanks may have a limited population of beneficial bacteria, and over-treatment can disrupt the delicate balance in the ecosystem.

Larger Aquariums

In the case of larger aquariums, adjusting the dosage becomes paramount. Ensuring that the right amount of conditioner is added is crucial for maintaining a safe and non-toxic environment for your aquatic friends.

Choosing the Best Aquarium Water Conditioner

Considering Different Products

When it comes to choosing the best water conditioner, it’s vital to consider the diverse range of products available. Different types of water conditioners cater to various aquatic animals and their specific needs.

Complete Conditioners

Some water conditioners go beyond simply neutralizing chlorine; they are known as complete conditioners. These products address multiple aspects of water chemistry, ensuring that your aquarium maintains the ideal parameters for your fish.

Years of Experience

Consider the popularity and longevity of a product in the market as an indicator of its effectiveness. Products with years of experience and a strong reputation are often a good starting point.

The Main Purpose of Water Conditioners

Chloramine Neutralizers

Water conditioners serve as chloramine neutralizers, rendering tap water safe by breaking down chloramine and chlorine. These chemicals, present in municipal water supplies, can be harmful to aquatic life.

Ammonia Control

Beyond chloramine, water conditioners help control harmful ammonia levels in the aquarium. Ammonia buildup can be detrimental to fish health, and a good water conditioner provides essential ammonia detoxification.

Stress Coat

Stress coat additives found in some water conditioners play a vital role in reducing stress among fish. This is especially important for delicate species like betta fish, promoting a healthier and more relaxed aquatic environment.

The Right Temperature and Water Chemistry

Matching Water Temperature

In addition to neutralizing harmful elements, it’s crucial to ensure that the water conditioner-treated water matches the right temperature for your aquarium. Sudden temperature fluctuations can stress your fish.

Maintaining Water Chemistry

Water conditioners help in maintaining the ideal water chemistry, ensuring that the pH, hardness, and other parameters are suitable for different types of freshwater fish and tropical fish.

Introducing New Fish to the Aquarium

Acclimating New Fish

When introducing new fish to your aquarium, it’s essential to use a separate container and conditioned water. This acclimation process reduces stress on the newly arrived aquatic animals.

Minimizing Stress

Water conditioners contribute significantly to minimizing stress in newly introduced fish. By providing a familiar and conditioned environment, your new fish can adapt more easily to their surroundings.

Regular Water Changes and Replacement Water

Importance of Regular Water Changes

Frequent and regular water changes are essential for maintaining a healthy aquatic environment. Water conditioners play a crucial role during these changes, ensuring that the water remains safe for your fish.

Treating Replacement Water

When adding replacement water during water changes, it’s important to follow guidelines for treating it with the right amount of conditioner before introducing it to your aquarium. This practice maintains consistency in water quality.

Ensuring a Safe Environment for Aquatic Animals

Creating a Safe Habitat

Water conditioners are instrumental in creating a safe and natural habitat for your aquatic pets. They transform untreated tap water into a environment that replicates their natural habitat, promoting their well-being.

Beneficial Bacteria

Maintaining beneficial bacteria colonies is crucial for a healthy ecosystem in your aquarium. Water conditioners help preserve these colonies, ensuring a balanced and thriving aquatic environment.

Differentiating Quality

When selecting a water conditioner, it’s essential to differentiate quality products from ineffective “snake oils.” Choose reputable and effective water conditioners that prioritize the health of your fish.

Popularity doesn’t always equate to the best option. It’s important to understand that the most popular product may not be the best option for your specific aquarium. Prioritize efficacy and reliability over popularity.

In conclusion, water conditioners are a vital component of maintaining a safe and healthy aquarium environment for your fish and aquatic animals. Understanding how to calculate the right amount, choosing the best product, and using it effectively can make a significant difference in the well-being of your aquatic pets. By following these guidelines, you can ensure that your aquarium thrives and remains a source of joy for years to come.


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