How to mix saltwater

How to Mix Aquarium Salt

You’re new to the hobby (or not). You’ve had your aquarium a couple of weeks, and it’s time to change your water. You don’t need a Ph.D. in Chemistry to choose the right salt mix for your aquarium. But different aquariums do have different water needs, so it’s important to consider the following when choosing your salt mix:

Does your aquarium house fish? Coral? Both?

What water parameters do you need to support life in your aquarium?

This might be a little overwhelming at first, but we’ll make it easy for ya! 😉 Kinny Parrott (our Parrott Aquatic Pro) has been keeping aquariums for about 28 years. He’s been through a lot of different salts and brands. Now, Parrott Aquatic eliminates the pains of trial and error by bringing you the highest quality aquarium saltwater. That’s why we use Fritz to produce our commercial RO Saltwater.


Fritz ProAquatics Reef Pro Mix (RPM)

Fritz RPM Salt

Fritz RPM Salt was balanced to achieve specific parameters that imitate real marine water. Just like Parrott Aquatic, Fritz also uses the highest quality raw materials available to manufacture their salt in-house in small batches for total quality control. Check out their claims for their RPM Salt below!

Fritz ProAquatics Reef Pro Mix (RPM)

  • Complete Professional Marine Salt Mix for Reef or Fish Only Systems
  • Contains All Essential Major, Minor & Trace Elements
  • Enhanced Buffer Levels; Reaches a Stable pH Shortly After Mixing
  • Enhanced Calcium, Magnesium and Potassium Levels
  • Nitrate, Phosphate & Ammonia Free
Fritz Reef Pro Mix
You can find products sheets for all of Fritz’s products on their website to learn more!

We trust Fritz RPM salt for all our customers and our own aquariums because we believe in their meticulous research.  Fritz began their research for the perfect aquarium salt by working with public aquariums and experts nationwide to determine the right base for their blend. Once they perfected their base, they reached out to us, the public, to determine the remaining balance.  After speaking with reefers from all over, they determined the most ideal water conditions for a saltwater tank.

Fritz’s ideal water composition looks like this:

  • Alkalinity: <9
  • Magnesium: 1400’s
  • Calcium: 400-420

Okay, I lied. There’s a little chemistry to it, but Fritz has already done the work for us! (Thanks, guys!) To achieve these ideal conditions, Fritz balances their salt like this:

Alkalinity: 8.5

Natural sea-water has an alkalinity of 7, but because this saltwater is in an enclosed thank, Fritz had to provide a buffer and chose to set the alkalinity of their salt to 8.5.

Magnesium: 1425

Fritz set the magnesium levels at 1425 to keep the proper bond between Calcium and Alkalinity. This prevents the calcium from causing the magnesium to “precipitate out causing the alkalinity to crash and creating a cloudy mix with precipitants all in the water. “

Calcium: 440

Fritz set their calcium balance to 440 to allow for a buffer during a water change.

We’ve learned a little bit about aquarium salt and its composition. So now I’d like for you to get your No. 2 pencils out, test sheets, and prepare for your exams. Eyes on your own papers. Be sure to fill in the circles completely and make your marks heavy and dark…Just kidding! (Phew, did that cause anyone else to have T-CAP flashbacks?)


We still need to learn how to mix RPM salt into the water so keep reading! Parrott Aquatic and Fritz recommend only mixing aquarium salt with 0TDS fresh RO Water to avoid foreign contaminants causing an imbalance.



It’s important to remember your aquarium safety when handling chemicals and water around electrical outlets.

  • Use caution when mixing water around electrical sources.
  • Always use a GFCI outlet for your power source to mix your salt. The ground-fault circuit interrupter, or GFCI, is a fast-acting circuit breaker designed to shut off electric power in the event of a ground-fault within as little as 1/40 of a second. It works by comparing the amount of current going to and returning from equipment along the circuit conductors. If you don’t have a GFCI outlet, you can purchase one from just about anywhere, but if you want to save time, here are some sample links to ones we have actually used.
  • Use an unbreakable heater, preferably one made of titanium. If your heater breaks, it will become an instant conductor between the water and electricity. Electric shock will occur.  
  • Store your salt in a dry place.  Salt exposed to moisture can clump and cause damage to your mixing pump, heater, and even decrease the quality of the salt.
  • Use a thermometer (because all heat sources are unreliable to some degree).
  • Choose a ventilated/open area to mix the salt to avoid breathing any chemicals.
  • Do not use wet hands to handle salt or place hands in water during mixing due to skin irritations and water temperature changes.
  • Use salt that has been stored in a dry place
  • Use eye protection to prevent eye exposure to dust and salt particles.

Also, I’m not saying you were going to – but don’t be a newb and mix the salt directly into your tank. The salt mixing process actually raises the temperature in your aquarium and could cause a lot of harm to your inhabitants! Anyways, keep reading for detailed instructions on mixing your own aquarium salt.

Aquarium Salt Mixing Materials


  • Clean Containers: Ensure your mixing container is clean. Only use it for saltwater mixing. Mark your container to prevent contamination.
  • Heater: Be mindful that if you are mixing a small quantity of water in your home or garage you may only need to raise the water temperature a few degrees so you will not need a huge heater to accomplish our goal of 70 to 75 degrees. A standard rule of thumb is 3 watts of heat for every gallon of water you are heating. So, if you have 10 gallons of water a 30-watt heater would be sufficient.  
  • Circulation Pump: Use a small one to keep your water moving when warming your water and adding salt. We recommend one rated slightly higher than the water volume you are mixing.
  • Calibrated Salinity Meter: A salinity meter measures the salt in the water, and ensures your salinity levels are accurate.
  • GFCI Protected Power Source: See Above.
  • Thermometer

How to mix your own saltwater


  1. Follow all instructions from the manufacturer carefully.
  2. Turn on your circulation pump in your clean container.
  3. Make sure your RODI water is 70 to 75 degrees before adding your salt.
  4. Add salt slowly.

Special Notes: Fritz salt mixes easily, unlike other brands!


Combining prepared saltwater with your tank

  1. Match the temperature of the mixed water with your aquarium.
  2. Test and ensure the ph is the same in both the aquarium and the new mix.
  3. Unplug your mixing container’s heater and pump when you are ready to use.
  4. Unplug the heater and pump in your aquarium.
  5. Drain the water you wish to remove.
  6. Slowly add the new water into your aquarium.
  7. Plug the pump and heater back in.
  8. Verify your water levels are correct and your heater is working.
  9. Clean your mixing container out with a little white vinegar and water
  10. Dry everything so you do not have any containments for next time!


What happens to your water?
Why shouldn’t you stick your hand in the water while it’s mixing? Because salt creates a chemical reaction causing the temperature to rise.

I asked Kinny a few more questions about mixing saltwater since he does this every day.  The Parrott Aquatic Shop is equipped to produce 1000 gal. of RO saltwater per day – I thought he would know a thing or two.

1. What happens if you use the wrong salt blend?

“We prefer Fritz for all our saltwater aquariums because of the quality and the clarity. After 28 years in this saltwater aquarium hobby, we have been through so many brands of salt! While I cannot state there is a wrong brand of salt. What I can say is investigate, read and determine if something other than Fritz RPM make sure understand the brand and what it may lack. “

2. What happens if you mix a salinity too high or too low?

“Don’t panic! If your salinity is high, slowly add more prepared water and retest your salinity. If your mix is low, simply add more salt until you achieve your desired levels.”

3. What are some pro tips/common mistakes to avoid?

“The biggest mistake we make as hobbyists is we get in a hurry and don’t let the water get within range before adding the salt. This can cause clumping of the salt and may damage your mixing pump. Also, the shortcut of not testing the ph and salinity can be devastating to your aquarium.  Lastly, make sure your mix has had enough time to mix thoroughly.”

4. How to mix in a small batch at home?

“Rubbermaid makes some awesome trashcans that suit our us just fine. They are listed as Commercial Brute Trash Cans. They have 20, 32 and 44-gallon sizes available at most hardware-type stores. So choose the size you need.”

5. What if I don’t have a mixing Pump? Use whisk?

“Well, I strongly suggest you hold off buying that next fish and purchase a pump for mixing. For good clean salt mixes, you really should use a small pump.  However, if you are only mixing a gallon, use a small bucket and a plastic spoon. Refrain from using anything metal. Small saltwater aquariums do exist in Nano tanks and even small bowls. Just use your best judgment and feel free to call with any questions.”


  • Use only RODI water for best results
  • Only use salt that has been stored in a dry place
  • When combining your water, make sure you have a couple extra gallons in case you spill any. You don’t want to come up short.

Aside from their RPM Salt, we carry a couple of other great aquarium products from Fritz. See what we keep in stock below or check out their website for a complete product list. We believe in Fritz. We trust their research and their products for our reef and yours. Stop by our self-service fill-up station at the shop. (Saltwater: .80/gal, RO Water: .40/gal)

Fritze Reef Pro Mix




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