18 Science-Based Tips About Synthetic Sea Salt Mix & Mixing Saltwater for an Aquarium
While it is possible to collect natural ocean water to use in your aquarium, by and large, the use of synthetic salt mix is the preferred route. Salt mix is often a dry powder designed to be mixed with RO/DI purified (0 TDS) water and contains all of the major, minor, and trace elements found in natural seawater.
The primary difference between various types of salt mixes is the ratio of elements and you should choose your salt mix based on the desired water parameters of your aquarium. All of the major brand-name salt mix companies have produced successful aquariums and the most important thing with salt mix is to stay loyal to the formula you choose. Switching or constantly changing salt mix will alter the elemental ratios of the water and likely create undue stress for your tank inhabitants.
1. Use a salt mix that most closely matches your tank's water parameters
It just makes sense to choose a salt mix that will produce water with the ideal parameters for your aquarium. Constantly trying to adjust the water parameters using chemical additives with every batch of saltwater you mix will only lead to inconsistencies. Not to mention, the cost of the additional chemical additives is always much more expensive compared to just choosing a more ideal salt mix from the get-go.
2. The most affordable salt mix that will produce good results is Instant Ocean
Instant Ocean has been around for many years and has produced thousands of successful saltwater and reef aquariums without issue. Keep in mind, this is the most affordable option but that doesn't necessarily mean it's the BEST option for you and your tank.
3. The quality of a salt mix is primarily based on the source of the sodium chloride
Sodium chloride makes up a majority (85%) of the material in your salt mix. Many reputable salt mix producers will actually advertise the source of sodium chloride in their mix. All sodium chloride is not created equal and some sources are purer than others. Lower-quality sodium chloride will carry impurities into your aquarium and wind up leaving residue in your mixing bins.
4. The quality and amount of magnesium dictate the final cost of the salt mix
High-purity magnesium chloride and magnesium sulfate are difficult to source and therefore will drive up the cost of a salt mix. Just like sodium chloride, magnesium is a common source of impurities in a salt mix, and using a high-quality source of magnesium results in a higher-quality salt mix.
5. Trace elements
Each salt mix is different in terms of how they approach trace elements. Some mixes will exactly match the ratios of natural seawater while others may boost certain trace and minor elements based on how corals typically consume them in a reef tank. If you're relying on your salt mix to maintain trace elements in your aquarium, choose a salt mix that specifically provides the proper ratios of trace elements. Research the particular mix and reference the advertised levels and if these measurements are not provided, it's probably not a reliable source.
6. A significant reason for inconsistencies in salt mix material is the batch mixing time of the raw materials
This refers to how much effort the producers are putting forth to create a completely homogeneous material. When mixing dry crystals of various chemicals in large batches, the mixing time is pivotal for ensuring each bucket or package of salt mix contains the proper ratio of elements. If a manufacturer tries to cut costs by reducing the mixing time, it will result in inconsistent ratios and parameters between batches.
7. Sludge buildup in your mixing container is an indicator of quality but is not toxic
Some salts will leave a residue or brown sludge in your mixing container because of various impurities in the salt mix. The severity can vary based on the particular batch of salt and while this is unsightly, the sludge is not poisonous or toxic to your fish and corals. The water is, generally speaking, perfectly safe to use in your tank.
8. Most salt mixes require 24+ hours to completely dissolve
Higher purity/quality salt mixes tend to dissolve quicker than lower quality salts. During our own BRStv Investigates experiments, many salts required 24+ hours to completely dissolve clear while only a few salts were able to dissolve within 1-2 hours. Coincidently enough, those quick-dissolving salts were also free of noticeable impurities.
9. Always test freshly mixed saltwater to verify parameters between batches
It is best practice to test parameters (salinity, pH, alkalinity, calcium, and magnesium) with each freshly mixed batch of saltwater to verify you're getting the results you think you are. At a minimum, test the first batch you mix from each new bucket/box of salt mix because parameters can change between different batches of salt, even if the salt is from the same brand.
10. E.S.V. B-Ionic Seawater System is the best solution for creating a consistent batch of saltwater but is also the most expensive
E.S.V. takes a unique approach by dividing up the elements into different components and providing specific mixing instructions that result in a completely homogenous solution that mixes fast with consistent parameters each and every time.
11. Stratification within the same container of salt mix is not really something that happens
Contrary to what you read online, a bucket of salt mix will not separate or stratify during shipping or storage. We tested this ourselves and could not identify a single mix that displayed a noticeable amount of stratification from the first to the last batch of saltwater.
12. Most salt mixes with normal parameters can be safely stored without heat and flow
After your initial mixing period, you can safely store mixed saltwater inside a sealed container with heat or water flow and parameters will not shift over time. This applies to salt mixes that advertise "non-elevated" or typical levels of calcium and alkalinity. Anything with elevated levels may experience precipitation without heat and flow.
13. Salt mixes with elevated parameters require heat and flow to avoid precipitation (and reduce sludge)
Any salt mix that advertises elevated levels of calcium, alkalinity, or magnesium should be stored with heat and flow to avoid precipitation, sludge, and shifting parameters. We discovered this during our BRStv Investigates series with Red Sea Coral Pro where the presence of heat and flow during long terms storage helped maintain the elevated levels. When Coral Pro water is stored for long periods of time without heat and flow, precipitation occurs causing a shift in parameters.
*Note: This phenomenon is somewhat contradictory to what science would lead us to believe because heat should, technically speaking, speed up the precipitation process as opposed to inhibiting it as we witnessed.
14. Based on a cost-per-gallon analysis, the difference between the most affordable and the best quality salt is negligible
Salt is a rare case where the cost of using the best quality product available isn't all that much more expensive than everything else.
15. Higher cost doesn't always mean the salt is better
Cost does not correlate directly to the quality of the salt but can be an indicator. The most affordable salt mixes cannot provide the highest quality salt because it costs too much to produce a high-quality mix. On the flip side, high cost doesn't necessarily mean the salt mix is high quality.
16. How to gauge the quality of a salt mix
Do your research when it comes to choosing a salt mix. Reputable brands will give you an accurate snapshot of the expected water parameters and make good on that promise with each batch of salt you mix. Some companies offer ICP testing results that can be referenced with a batch number so you can know exactly what to expect. The highest quality salt mixes use graded raw materials for purity and consistency with every batch and will advertise as such.
17. Read the instructions, each salt mix is unique!
It's easy to fall into a routine when it comes to mixing saltwater but if you're not mixing your salt correctly, this routine could be working against you. Always read the manufacturer-provided mixing instructions so you can be sure you're getting the best possible results. Following the mixing instructions will reduce the chances of precipitation and in some cases, reduce the formation of sludge.
18. Although it's rare, a bad batch of salt mix occasionally happens
The most common reason for a bad batch of salt is caused by insufficient mixing times with the raw materials which lead to batches of salt with incorrect parameters. Usually indicated by calcium or alkalinity levels being extraordinarily high or low. There is also the exceedingly rare case where a batch is contaminated with something (toxin) that is harmful to the aquarium.
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