The Best Methods For Mixing Saltwater Using Synthetic Salt Mix - BRStv FAQs

Mixing reef salt mix CORRECTLY will result in less precipitate and brown crust in your mixing and storage containers, more stable initial water parameters, and presumably, avoid any negative health benefits associated with dosing undissolved salts into your saltwater aquarium. It is safe to assume exposing fish gills and coral tissue to undissolved salt crystals is not healthy, even if it isn't immediately toxic.

We are not talking about the bare minimum process to mix salt and keep the tank alive. Instead, we want to provide all of you with the absolute best practices for mixing saltwater yourself with optimal parameters and reducing build-up in your mixing and storage bins. BRStv has performed all kinds of salt mixing experiments and this is a culmination of tips and best practices based on those results. 

If you are just interested in a quick tutorial, you can skip to the Step-By-Step Salt Mixing Instructions at the bottom of this page.

Follow the instructions, it’s a no-brainer!

The first thing we learned is you should always follow the instructions on the bucket, they are printed for a reason. All of these salts come from different sources of mined, evaporated, or purified synthetic salts and have different levels of major elements. Some even contain extra additives such as chelators and clarifiers which will change how the salt mixes up.

While all of the available salt mix options we carry will support marine life, they are not the same, particularly when it comes to the mixing process. Some are less dependent on strictly adhering to the instructions for optimal results but if you are looking for best practices, the manufacturer is going to be the best place to start.

How long should I mix the water?

We asked the reefing community how long they mix their salt and for such a necessary process, the answers were surprisingly all over the place. 29% of hobbyists said you only mix for an hour or less, another 3rd of the poll participants said 12 hours or more, so which one is correct or best practice?

In our experiment of unheated water with two powerheads mixing up 20 gallons of saltwater, the necessary length of time to create visually homogeneous saltwater varied dramatically. Starting at around 7 Hours to many of the salts not even fully dissolved at 24 hours.

Considering many of the salts we mixed were not fully homogenized or dissolved at 24 hours, I think the best general advice is to mix it for 48 hours.

Helpful Tip: This means you need to plan ahead at least two days before a scheduled water change and even longer if you need time to collect purified freshwater using an RO/DI system.

As mentioned above, we tested 8 different brands of salt mix, and the results varied widely in terms of exactly how long each salt mix needed to fully dissolve. These are the brands that successfully mixed in less than 24 hours which is beneficial for those of you looking for something that will mix up a little quicker.

• Red Sea Blue Bucket: 23 Hours
• HW Reefer: 23 Hours
• Brightwell Aquatics NeoMarine: 21 Hours
• Tropic Marin Pro Reef: 8 hours
• Tropic Marine Classic: 8 Hours

The only thing to note here is the two powerheads warm the water to around 76° F on their own but we did NOT add an aquarium heater to the water during this test. Some salt mix brands do call for heating in the mixing instructions and using a heater set at 78° F may hasten the time it takes to fully dissolve the dry salt mix. 

Do I need to heat the water when mixing it?

Again there isn't a one size fits all answer to this one. Our experiments show that the best practice answer to that question is, yes but it is not critical so long as you give the salt enough time to dissolve.

After all of this testing at the same specific gravity, we recommend heat and flow for at least the first 24-48 hours as a best practice for all salt mixes.

That being said, if you're in a pinch mixing can be scaled all the way down to only a couple of hours of mixing with no heat for select high-quality salt mixes, most notably Tropic Marin Pro Reef and Brightwell Neomarine. Both of which seemed to repeatedly perform well in all the experiments and probably require the least amount of time, equipment, and effort to mix and store safely without residue or contaminants.

How long can I store mixed saltwater?

Storing the water properly is important because many of us are mixing large batches of saltwater and storing it for use throughout the month; if not stored correctly the chemistry of the water may change resulting in varying tank parameters. It is best to store your mixed saltwater without a heater or pump. Use a tight-fitting lid to keep out light and debris/contaminants. 

You can safely store saltwater for 30-60 days without an ill effect so long as you have a tight-fitting lid.

Once you are ready to use the water, simply add a pump and heater to help oxygenate the water and bring it up to temperature before using it in your aquarium. 

How To Mix Saltwater - Step By Step

1. Fill the entire mixing container with fresh RO/DI water. It's important to fill with the entire volume of water first. You should never gradually add water to the salt mix, rather slowly add salt into the water. 
2. Read instructions for the particular salt mix you are using. Add a pump or powerhead and turn on the heater to bring the water up to 76 - 78° F.
3. Measure the appropriate amount of salt mix as instructed (usually right around 1/2 cup per gallon of freshwater to reach 1.026 or 35 PPT salinity).
4. Carefully add the salt into the water, 1/2 cup at a time.  Let it dissolve, then add a little more until you have added all of the previously measured salt mix. 
5. Let the water mix and aerate for up to 48 hours or as recommended by the manufacturer. Some salt mixes should only be mixed for 3-4 hours like Red Sea Coral Pro but a majority of them will do best with 24 hours of mixing.
6. Test salinity using a refractometer or hydrometer. You can add a little more salt to bring up the salinity or add some fresh RO/DI water to bring the salinity down.  
7. Use the water in your aquarium or store the salt as directed above.