There have been quite a few studies of the various salts available to hobbyists over the last few years, with each promising rigorous procedures and high levels of accuracy. The results have certainly been interesting, and sometimes controversial. The one thing that these studies have taught is that it’s important to remember that variability seems inherent, even within the same brand of salt. The way it is tested, stored, the amount used and even the way it is added to the tank may all affect the parameters obtained. Nonetheless we thought it would be interesting to share our own casual observations as we brewed-up 100 gallons of fresh mix for the new test tank.
For this review, we’ll be concentrating on just one brand of salt and, as we’ve had good results from using it for several years, on a number of different setups, ReefCrystals remains our chosen mix.
Before we even open our 25kg bucket, lets say that the new packaging looks great and we’ll certainly be using this bucket, once empty, again. As you’d expect, the bucket is completely fit for purpose and the lid snaps shut nicely, keeping your mix nice and dry indefinitely. On this subject, we’ve already mentioned that the way salt is stored can sometimes have an effect on the results. To explain, what we are talking about here is ‘settling’ where small grains may work their way to the bottom of the bucket gradually over time resulting in stratification of the substances in the mix. To combat this, we’d normally roll and tumble the bucket, but on this occasion we’ve gone a step further and poured it completely into an empty bucket and then back again.
With the entire large batch now thoroughly mixed, and our test tank filled with RO/DO water (measured 000 TDS) at 24.5degC, we began to add it. To do this we used a clear 500ml pyrex jug, taking about 15 seconds to pour each ‘scoop’ of dry mix from the bucket into the display. With pumps providing a turnover rate of 30 tank volumes per hour, the salt dissolved quickly in the display with any larger crystals that reached the tank floor eventually dissolving after 20 minutes or so. In our approx. 550 litre sytem, we used just over 20kg to obtain a Salinity reading of 35ppt (37ppt on our DI calibrated ‘brine’ refractometer)
So what readings did we get anyway? Well, we waited 24hrs first to ensure the mix had completely dissipated and levels had stabilised (this is how long we’d usually leave a new batch of salt for a water change also). The readings we then obtained were:
Calcium: 430ppm Red Sea Pro Kit – 407ppm with Hanna Checker
Alkalinity: 11.9 dKH Red Sea Pro Kit
Magnesium: 1340ppm Red Sea Pro Kit
Phosphate: 0.05 Hanna Phosphorous ULR Checker
Nitrate: 0 Red Sea Pro Kit
Iron: 0 – 0.05ppm Red Sea Coral Colours Pro Kit
Iodine: 0.03 – 0.06ppm Red Sea Coral Colours Pro Kit
Potassium: 400ppm Red Sea Coral Colours Pro Kit
As we can see from the results above, mineral levels were all pretty much spot on. The high Alkalinity was reassuring for the set-up of a new system and we don’t think this could impact stability of established systems if water changes are not too large. Nitrate levels were undetectable. Major trace element levels also all appeared fine. Phosphate was pretty much on the limit for coral systems but we aren’t to concerened about this for a new system (with no corals in it), and with established systems the rise in Phos caused by adding a typical water change amount shouldn’t add up to much and would be taken out by algae/resins quickly.
In conclusion, while we didn’t use a government lab to test our sample, we did do the research and stuck to basic ‘good practice’ guidelines to ensure we got the best results from our hobbyist level kit. The results are certainly interesting, and suggest that the salt is indeed entirely suitable for purpose giving water of correct mineral levels and major trace elements. The review becomes perhaps more interesting when viewed in tandem with historical studies and perhaps gives us an idea which of those studies are the more reliable.