How To Mix Salt for Saltwater Aquariums

In this post we are going to answer the question, How to Mix Salt for Saltwater Aquariums. I’ll also post a link to my YouTube tutorial at the end of this post.

If you’re setting up a new saltwater aquarium or maintaining an existing system, mixing salt and water to achieve a desired salinity will be a necessary step in either process. I’ll quickly cover what you’ll need.

Aquarium Salt

The first thing you’ll need is salt. There are a lot of options to choose from so before selecting a salt have a good understanding of what livestock (fish and/or coral) you plan to keep. If you’re only keeping fish there are less expensive options you can buy because a fish only saltwater aquarium doesn’t really need a high quality salt. If you’re keeping live corals though, you’ll want to pick a higher quality salt. I like the Tropic Marin line of salts for my saltwater aquariums that contain live corals.

RODI Water

I strongly recommend you use reverse osmosis deionized water, also known as RODI water when you’re setting up your saltwater aquarium. You can purchase RODI water at a local fish store or purchase filter kits that will allow you to purify tap water and make it RODI water.

Saltwater Mixing Container

Once you have your salt and water, you’ll need something where you can mix the two. There are a couple bargain options like a standard 5-gallon bucket but I like to use a 20 gallon Brute trashcan to mix my saltwater. The Brute trashcans come with attachable wheel bases that help you move around much easier.

Saltwater Stirring Device

You can use any long aquarium safe stick but what I like to use is a cheap AC powerhead. Using a powerhead will allow you to continually mix the salt and water without having to do it manually.

Salinity Measuring Device

You’re going to want to test the salinity of the water you’ve just mixed before adding it to the tank. Salinity is defined as the concentration of salt in water, basically how salty is the water. In home aquariums most hobbyists maintain levels at 35ppt or 1.025 specific gravity. I like to use a refractometer to test the salinity.


It’s a good idea to use a heater when mixing your salt and water. If your RODI water is colder than the aquarium water, you’ll want to make sure the water is warmed to match the temperature of your saltwater aquarium. I personally like to mix my salt and water the day before I do a water change, in order to give the salt time to completely dissolve and to also allow the overall mixture to get to the temperature I need.

The Saltwater Mixing Process

Once you have your heater and powerhead situated in the mixing container, you can add your water. After the water is added, you can plug in the heater and powerhead to start warming and moving the water. To mix to the proper salinity you will need to check the label on your salt to find the recommended amount of salt needed to achieve your desired salinity. Add the recommended amount of salt and let the powerhead mix for a bit and test your salinity with the refractometer. Wait until the cloudiness goes away before testing.

Once you’ve measured 35ppt or 1.025 specific gravity you’re done, just let the powerhead continue to mix for the next 24 hours while the heater gets the water to the desired temperature.

Video on Mixing Salt for Saltwater

If you’re more of a visual learner you can watch my YouTube tutorial on how to mix salt for saltwater aquariums:

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