All marine salt mixes are not created equal and we have uncovered some very interesting facts about mixing saltwater at home in our recent series of BRStv Investigates videos about testing salt mix.


Abruptly switching salt mix brands for use in your saltwater tank often comes with setbacks. So we set out to answer the looming questions on this subject and provide you with the best approach to switching salt mix without putting your tank through the ringer.


Salt Crystals Macro Image


Why does switching salt mix cause problems?

The presumption that switching from a lower to higher grade salt mix will only benefit your tank is not always exactly true. We can confidently assume this has to do with the different chemical make-up of the various brands and the way corals respond to their environment.


The ratios of major, minor and trace elements are different in each salt mix brand, some more desirable than others. Abruptly switching the mix will surely throw off the balance in your tank.


Tropic Marin Pro Reef Parameters


Choose a new salt mix that closely matches your current tank conditions or previous salt mix with similar major elements of calcium, alkalinity and magnesium levels.


In many cases, however, the reason for switching is to either significantly increase, decrease or otherwise change the water parameters in your display tank so choosing something similar would be counterintuitive.


Making a slow and incremental transition to a new saltwater mixture is best to prevent stress on the tank inhabitants.


Evaporated Sea Salt


The second part of it is the varying impurities which is inherent because of the different sources that manufactures use to acquire the major components of a salt mix. These source materials go through varying degrees of purification ranging from adequate to intense pharmaceutical grade processes which then leave us with varying degrees and types of impurities.


What happens in your tank is that corals, being amazingly adaptable creatures, get used to the impurities and general chemical make-up of your chosen salt mix over time. So when you switch it up abruptly, the corals get stressed without the appropriate time to adapt to the new conditions.


Tortoise and The Hare


Just like pretty much all aspects of successful reefkeeping, making large and “fast” changes almost always ends up in disaster. Slow and steady wins the race every time.


Do you really need to switch?

First things first, decide if you really need to switch because if your tank is doing well and meeting all your goals just stop in your tracks and don’t bother switching. Don’t switch because some brand has a better label or marketing hype either, instead look for a more definable aspect in your new salt mix.


  • 1. Cost - the most economical option that works for you is obviously attractive.
  • 2. More closely matches the desired calcium, alkalinity and magnesium levels than your current salt mix.
  • 3. Mixes faster - meaning it is ready for use in a few hours rather than a few days.
  • 4. Mixes easier - some salts require heating and prolonged circulation for successful storage.
  • 5. Doesn’t contain visible contaminants - not all salt mixes will leave crust or create brown organic foam on the surface during mixing and storage.
  • 6. Provides clear sustainable quality or purity standards beyond the typical marketing hype. For example, Red Sea’s MyBatch ICP test results or Aquaforest’s Quality Certificate. Topic Marin’s approach of meeting an independant standard of quality by using only pharmaceutical grade raw materials is another example.


Don’t be fooled by promises of “...it grows coral better or worse than another” because this is completely anecdotal and subjective. While it is true that one salt will certainly perform better than another, don’t focus on the “best” because it doesn’t exist. Instead pick one of the better options that has some aspect that will make your life easier in terms of keeping a healthy reef tank.


Water Change Schedule


How to switch salt mix

There are two distinct paths based on your water change schedule that will limit the impact on your tank or essentially avoid any drastic changes in water chemistry.


Auto Water Change System with Neptune DOS



When performing small frequent water changes at the rate of 10% weekly or using an automated water exchange system for daily water changes in the 1-3% range, than you can just mix up a batch of 100% new saltwater and proceed as normal.


The small incremental water changes means you will not run the risk of making major changes to the tank’s chemistry, it will happen slowly based on this water exchange schedule. This approach is becoming more and more popular because of the great results and advancements in aquarium technology making it much easier to implement.


Saltwater mixing station


If you are on the more classic regime of 20% bi-weekly or 30-40% monthly water changes, you will want to adjust your mix as follows.


  • 1st Water Change - 25% new salt and 75% old salt
  • 2nd Water Change - 50% new salt and 50% old salt
  • 3rd Water Change - 75% new salt and 25% old salt
  • 4th Water Change - 100% new salt from here on out


When doing this, do not mix the old and new dry salt mix together at the same time. Instead, mix up your old saltwater separately from the new saltwater, both to your desired salinity level. Then follow the ratios above and replace the water from your tank after you have mixed each brand of salt separately.


Of course, pay attention to how the tank responds and slow the process down if you think the tank would benefit. Every tank is different and this is a general guideline that will provide you with an idea of how to make a slow transition to a new salt mix.


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