How to Mix Saltwater

Saltwater Aquarium 101

How to Mix Saltwater

How to Mix Saltwater for the Aquarium.

Mixing saltwater

Mixing saltwater as a beginner in the saltwater aquarium hobby, can be frustrating. It took me the better part of my first year to get it down, and make the process become second nature for me. Today, the way I mix saltwater is done on a much larger scale due to the fact that I maintain over 1200 gallons of saltwater aquariums. The the purpose for mixing saltwater is to replace the water that you remove during water change. Aquarium water changes play an important role in maintaining a saltwater aquarium.

In this article I will give you the basics of how to mix saltwater for your saltwater aquarium. I will break down the  supplies needed and give you a step by step guide for mixing saltwater for your aquarium at home.

Things you will need for mixing saltwater:

To get started with mixing saltwater you will need a few things.

  • Synthetic salt mix
  • Refractometer or hydrometer
  • Mixing container
  • Powerhead
  • Submersible heater
  • Thermometer
  • Reverse osmosis water (RO/DI water)


Synthetic salt mix:

  • There are many Salt mixes available on the market today. I used Reef Crystals made by Instant Ocean (I’m not compensated in any way for saying that, but if Instant Ocean wants to, I’ll say it a lot more…….  just saying, lol). As a New Hobbyist I would suggest buying the smallest bag of salt mix as you can and try them all and find what brand works best for you.

Refractometer or hydrometer:

  • The Refractometer or Hydrometer is one of the most import pieces of saltwater aquarium equipment you can own. These devices measure the amount of salt in saltwater. It’s very important to maintain a specific gravity (or sg.) level of 1.023 – 1.025 in a saltwater aquarium.

Mixing container:

  • Any container used for mixing saltwater should only be used for mixing saltwater and made of a food grade plastic. The size of the container depend on your needs. If you are mixing saltwater for a 55 gallon aquarium (or smaller) a 5 gallon bucket should work fine. For larger aquariums, you may want to consider a Brute trash can, it’s made of food grade plastic and can hold up to 55 gallons of water.


  • A powerhead can help speed up the process of mixing saltwater and can help improve dissolved oxygen levels by breaking the water surface. Again, it’s a good idea to have a designated powerhead used only for mixing saltwater.

Submersible heater:

  • A submersible heater will help insure the water is the same temperature as the water in the aquarium. This will help avoid temperature shock then you add the water to the aquarium.


  • Using a thermometer will help you monitor the temp of the water and make sure it’s in range so the water can be added safely to your aquarium.

RO/DI water:

  • Reverse osmosis unit is a simple form water purification. Water straight from the tap often has excessive amounts of chlorine, copper, nitrates, nitrites, phosphates and many other metals and chemicals. These contaminants are vary harmful and possibly deadly, to sensitive marine fishes, invertebrates and corals. 


How to mix saltwater step by step:

  1. Add RO/DI water to your clean saltwater mixing container
  2. Add submersible heater and powerhead
  3. Add synthetic salt mix (following manufacturer’s instructions).
  4. Turn on Pump and Heater.
  5. Cover Container and let set overnight.
  6. Check salinity with refractor meter and or hydrometer.
  7. Check temperature.
  8. Complete water change.


How To Mix Saltwater video:


Mixing saltwater for your aquarium will become more easy with time. If you follow these steps and put them to work I would be willing to bet this task will become more simple to complete. I hope the article was helpful and please do not hesitate to drop me a line with any questions.

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