How to Change Aquarium Water: A Comprehensive Guide

A Clean Aquarium is a Happy Aquarium

Welcome, aquarium enthusiasts! It’s no secret that owning an aquarium requires dedication, hard work, and attention to detail. One of the crucial tasks that come with owning an aquarium is changing the water. Changing aquarium water can be a daunting task, but fear not! In this article, we’ll provide an easy-to-follow guide on how to change aquarium water properly. We’ll also discuss the advantages and disadvantages of changing aquarium water and provide answers to frequently asked questions. So, let’s dive in!

Step by Step Guide to Changing Aquarium Water

First things first, let’s go over the materials you’ll need before you begin:

Materials Quantity
Bucket 2 (one for dirty water and one for clean water)
Gravel Vacuum 1
Clean Towels or Paper Towels As Needed
De-Chlorinator As Recommended by the Label
Water Test Kit 1

Step 1: Turn off Filters and Heater

Before you start, it’s important to turn off all aquarium equipment such as filters, heaters, and air pumps. This will prevent any damage to your equipment and keep your fish safe.

Step 2: Remove and Replace Water

Using a gravel vacuum, remove 10-20% of the water (depending on the size of your aquarium) and dispose of it in the bucket you designated for dirty water. Fill the bucket designated for clean water with new, fresh water that has been treated with De-Chlorinator.

Step 3: Clean Filter and Gravel

While the dirty water is still draining from the aquarium, you can take the opportunity to clean the filter and gravel. Rinse the filter media with the water you removed from the tank, being careful not to damage the delicate bacteria colonies. Clean the gravel using the gravel vacuum and rinse it with water from the bucket designated for dirty water.

Step 4: Refill the Aquarium

Once you’ve disposed of the old water, refilled with fresh, treated water, and cleaned the filter and gravel, you can turn the equipment back on and fill the aquarium to the appropriate level. Use a water test kit to ensure that the water’s pH, ammonia, nitrite, and nitrate levels are within the appropriate ranges for your fish and plants.

Step 5: Repeat Regularly

It’s essential to maintain a regular schedule for changing aquarium water. For most aquariums, changing 10-20% of the aquarium water every 1-2 weeks is sufficient. However, this may vary depending on your fish and plant needs.

Step 6: Observe Fish Behavior

After changing the water, keep a close eye on your fish’s behavior. If they seem distressed or agitated, check the water conditions using a water test kit.

Step 7: Enjoy Your Clean Aquarium!

After following these steps, your aquarium will look clean and fresh, and your fish will be happy in their new environment.

Advantages and Disadvantages of Changing Aquarium Water


1. Removes Excess Nutrients: Changing the aquarium water removes excess nutrients that can harm your fish and plant life.

2. Maintains Water Clarity: Regular water changes help maintain the water’s clarity, making it easier to observe your fish and plants.

3. Promotes Fish Health: Clean water promotes fish health by reducing the risk of disease and infection.

4. Reduces Algae Growth: Excess nutrients and waste can lead to algae growth, which can harm your fish and plants. Regular water changes can help prevent algae growth.


1. Stressful for Fish: Changing aquarium water can be stressful for fish, especially if the water chemistry is significantly different.

2. Destroys Beneficial Bacteria: Changing too much water or using chlorinated water can harm beneficial bacteria, which are essential for maintaining water quality.

3. Time-Consuming: Changing aquarium water can be a time-consuming task, especially for larger aquariums.

4. Expensive: Frequent water changes can be expensive, especially if you’re using a water treatment solution.

FAQs About How to Change Aquarium Water

1. How Often Should I Change my Aquarium Water?

The frequency of water changes depends on the size of your aquarium, the number of fish and plants, and your filter’s capacity. Generally, it’s recommended to change 10-20% of the aquarium water every 1-2 weeks.

2. Can I Change Too Much Water at Once?

Yes, changing too much water at once can harm your fish and beneficial bacteria. The recommended amount is 10-20% of the aquarium water.

3. Do I Need to Use De-Chlorinator?

Yes, it’s essential to use De-Chlorinator to remove chlorine and other harmful chemicals from tap water.

4. Can I Use Tap Water to Refill my Aquarium?

Yes, you can use tap water to refill your aquarium. However, it’s essential to treat the water with De-Chlorinator before adding it to your aquarium.

5. Can I Change Aquarium Water With Fish in the Tank?

Yes, you can change aquarium water with fish in the tank. However, it’s essential to minimize stress for your fish by changing the water gradually and ensuring that the water temperature and chemistry are consistent.

6. What Should I Do If My Fish is Stressed After a Water Change?

If your fish appears stressed after a water change, check the water conditions using a water test kit. If the water parameters are not within the appropriate ranges, adjust accordingly. You can also add aquarium salt to the water to help alleviate stress.

7. How Do I Clean my Gravel?

To clean your gravel, use a gravel vacuum to remove debris and waste. Be sure to rinse the gravel with water from the bucket designated for dirty water.

8. Can Cleaning the Filter Harm my Fish?

Cleaning the filter can harm your fish if you remove too much beneficial bacteria. Be sure to rinse the filter media with water from the bucket designated for dirty water, as this will help preserve the beneficial bacteria colonies.

9. How Do I Know If my Aquarium Water is Safe for my Fish?

Use a water test kit to check the pH, ammonia, nitrite, and nitrate levels in your aquarium water. Each fish species has specific water parameter requirements, so be sure to research your fish’s needs before adding them to your aquarium.

10. Do I Need to Change the Water Filter?

It’s essential to replace filter media regularly, as it can become clogged and reduce the efficiency of your filter. Follow the manufacturer’s instructions for replacement intervals.

11. Can I Change the Water During Winter?

It’s recommended to avoid changing aquarium water during winter because cold tap water can shock your fish and affect their health.

12. Do I Need to Turn off my Aquarium Lights Before Changing the Water?

Turning off your aquarium lights before changing the water can help minimize stress for your fish. However, it’s not necessary to turn off the lights.

13. How Do I Remove Excess Algae?

You can remove excess algae by cleaning the aquarium glass with an algae scraper or by reducing the amount of light your aquarium receives. Regular water changes can also help prevent algae growth.


Changing aquarium water may seem overwhelming, but it’s a vital task for maintaining a healthy environment for your fish and plants. Follow the step-by-step guide we’ve provided, and you’ll be able to change aquarium water like a pro! Remember to be consistent with routine water changes, observe your fish’s behavior, and monitor the water’s pH, ammonia, nitrite, and nitrate levels. With a little effort, you’ll have a clean, healthy aquarium that you can enjoy for years to come.

So what are you waiting for? Grab your bucket, gravel vacuum, and get to work! Your fish are waiting.

Closing Disclaimer

The information in this article is for educational purposes only and is not intended to replace professional advice. Before making any significant changes to your aquarium’s water or environment, consult with a veterinarian or a trained aquarium specialist. Remember to use caution when handling aquarium equipment and follow all safety precautions.

Watch Video:How to Change Aquarium Water: A Comprehensive Guide