Salinity is THE one parameter that matters the most in a saltwater aquarium or reef tank, and we’re always coming across new tools to measure the salt in our water. The Serenity MS-31 is the newest addition to the seawater measurement toolbox and it’s part of a new wave of more accurate testers using electrical conductivity.
Priced at AU$129 or around $100 in the U.S., the Serenity MS-31 is very small and light and uses a special insulated measuring cup to isolate errant voltage which would interfere with its measurements. It’s important to note that the MS-31 is NOT a digital refractometer as advertised by online vendor Serenity – this is an EC meter all the way.
Likewise, most reefers will be tempted to use the big bold specific gravity reading to determine salt concentration but you’ll be much better off using the percentage readout. In this video example you see the user measure salt with the MS-31 and seems pretty satisfied with his specific gravity of 1.025. But when the display cycles to percentage of salt, it only reads 2.99% – equal to 29.9 Parts Per Thousand (PPT) when you should actually be aiming for the same salinity as the ocean, 3.5% or 35ppt.
If you just relied on the specific gravity readout, you could be lulled into a false sense of security of believing your salinity is accurate when in fact it could be very low like in this example. This is why no matter what kind of fancy measuring tool you are using, it’s very important to truly understand how it fundamentally works. [Serenity]