I just bought a C-scope refractometer. It says to use distilled water to calibrate it. Can I use the RO/DI water that I'm filling my tank with? Yes said:
That's a common question and one that doesn't really have a great answer. You should be able to use it, but that depends on how well your unit is pulling stuff out. Distilled by its nature should have most if not all the impurities removed. RO/DI should remove most of them, but the natural salts etc in the water may still slip through depending on your unit and your maintenance. Then you toss the manufacturers recommendation of using H20 to calibrate saltwater.... there is a lot of ongoing debate on that itself.
I use the pinpoint salinity probe fluid myself, others use a homemade calibration solution. The theory behind it is that you calibrate to a known salinity that is identical to what you are trying to maintain in the tank. Since this already has the salt in the equation, the though it is it will be more accurate.
I think you'll be much better using either method, compared to a swing arm, but you still may be off a tad using H20 only.
