How to Make Ocean Water – Create Your Own Natural Saltwater for Your Aquarium


Welcome to our guide on how to make ocean water! If you’re a passionate aquarium hobbyist or just curious about the science behind creating saltwater, you’ve come to the right place. Making ocean water is simple, but it takes a little know-how to get the perfect balance of salt and minerals for your aquarium’s inhabitants to thrive.

Creating your own ocean water is an affordable and sustainable option for aquarium owners. It eliminates the need to purchase premade salt mixes, which can be pricey and may contain unnecessary additives. It also gives you full control over the composition of your aquarium water, ensuring that your fish, corals, and other marine life can grow and flourish in a healthy environment.

In this article, we’ll walk you through the steps of making your own ocean water, explain its advantages and disadvantages, and provide answers to frequently asked questions. Let’s dive in!

How to Make Ocean Water

Step 1: Gather Your Supplies

Before you can begin making ocean water, you’ll need to gather the appropriate supplies. Here’s what you’ll need:

Supply Quantity
Marine salt mix 1 lb per 4-5 gallons of water
Dechlorinated tap water As needed
Hydrometer 1
Large mixing container 1 (at least 5 gallons)
Stirring stick or powerhead 1

Step 2: Mix the Salt and Water

Once you have your supplies, it’s time to start mixing your ocean water. Here’s how:

1. Fill your mixing container with the appropriate amount of dechlorinated tap water based on the size of your aquarium.

2. Slowly add the marine salt mix to the water, stirring continuously with a stick or powerhead to distribute the salt evenly.

3. Use a hydrometer to measure the salinity of the water. The ideal salinity for most saltwater aquariums is between 1.020 and 1.025 Specific Gravity (SG). If the salinity is too low, add more salt mix; if it’s too high, add more water.

4. Continue stirring until the salt mix has fully dissolved and the salinity is within the desired range.

Step 3: Test the Water

Before adding the water to your aquarium, it’s important to test it for pH, nitrite, nitrate, and ammonia levels. These levels should be at their optimal ranges for the best environment for your marine life.

Step 4: Add the Water to Your Aquarium

Once you’ve tested your water and confirmed that it’s safe for your marine life, you can add it to your aquarium.

Step 5: Monitor Your Aquarium

After adding your ocean water to your aquarium, closely monitor the water parameters and adjust as necessary. Keep an eye on the salinity, pH, and temperature levels, and make any necessary adjustments to ensure a healthy environment for your marine life.

Advantages and Disadvantages of Making Ocean Water


1. Control over water composition: Creating your own ocean water gives you full control over the salt and mineral levels in your aquarium. This is especially important for sensitive creatures such as corals and invertebrates.

2. Cost-effective: Making your own ocean water can save you money in the long run, as you won’t have to purchase premade salt mixes.

3. More sustainable: By making your own ocean water, you can eliminate packaging waste and reduce your carbon footprint.


1. Time-consuming: Mixing your own ocean water takes time and effort, which may not be practical for some aquarium owners.

2. Risk of improper mixing: If the salt and mineral levels are not properly balanced, it can harm your marine life.

3. Inconsistent results: Even if you follow the same recipe, it’s possible to get slightly different results each time you make ocean water, which could affect the health of your marine life.


1. Can I use tap water to make ocean water?

Yes, but it’s important to dechlorinate it first. Chlorine can be harmful to marine life, so use a dechlorinating agent or let the water sit for 24 hours before using it for your ocean water mix.

2. How often do I need to change my aquarium water?

It’s recommended to change 10-20% of your aquarium water every two weeks to maintain healthy water parameters.

3. Can I use sea salt instead of marine salt mix?

No, sea salt contains impurities and contaminants that can be harmful to your marine life.

4. Can I store extra ocean water for later use?

Yes, you can store the unused ocean water in a clean container with an airtight lid for up to one week.

5. How long should I wait before adding marine life to my aquarium after adding new water?

It’s recommended to wait at least 24 hours to let the water parameters stabilize before adding any new marine life.

6. Is it necessary to aerate the water while mixing?

No, it’s not necessary, but it can help speed up the dissolving process and ensure an even distribution of minerals.

7. Can I adjust the temperature of the ocean water before adding it to my aquarium?

Yes, you can adjust the temperature by heating or cooling the water before adding it to your aquarium.

8. How can I tell if my ocean water mix is too salty?

If the salinity of the water is above 1.025 SG, it’s too salty and can harm your marine life. Use a hydrometer to measure the salinity and adjust as needed.

9. What is the difference between marine salt mix and reef salt mix?

Marine salt mix is designed for a general saltwater aquarium, while reef salt mix includes additional trace elements that are essential for coral growth.

10. How does ocean water compare to freshwater for aquariums?

Ocean water is necessary for marine life, while freshwater is necessary for freshwater species. It’s important to use the appropriate water type for your aquarium inhabitants.

11. Is it safe to use ocean water if I live near the ocean?

No, ocean water near shorelines can contain pollutants and contaminants that can harm your marine life. It’s best to make your own ocean water using marine salt mix and dechlorinated tap water.

12. Can I add freshwater fish to a saltwater aquarium?

No, freshwater fish are not adapted to survive in saltwater environments and will not thrive.

13. How can I prevent algae growth in my aquarium?

To prevent algae growth, limit the amount of light your aquarium receives, maintain appropriate nutrient levels in the water, and perform regular water changes.


There you have it – the complete guide on how to make ocean water for your aquarium. Creating your own saltwater is a cost-effective and sustainable option for aquarium owners, and it allows you to have full control over your aquarium water composition.

Remember to always test your water parameters and make adjustments as necessary to ensure a healthy environment for your marine life. With a little knowledge and effort, you can create the perfect ocean water mix for your aquarium and enjoy a thriving marine ecosystem.


The information provided in this article is for educational purposes only. Always consult with a professional aquarium service provider before making any changes to your aquarium’s water composition or adding new marine life. We are not responsible for any damage or harm caused by the application of the information in this article.

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