digital vs naked eye you decide

[sphelps]

So it requires some kind of solution for calibration, ideally I would assume something like NSW. I would assume RO water not being good enough to produce accurate results?

[Aqua-Digital]

Yes, all digital meters require solution. It is unimportant whether NSW or NACL as it does not get effected by mineral or impurities, unlike refractometers. The only two key points are

1. the solution is within ppm range of the manufacturers calibration guideline
2. you are confident in its accuracy

with digital meters it is often best to use the supplied manufacturers solution.

[The Guy]

I have a refractometer and use it only for SW, I have calibrated it a couple of times, but I have never had to make adjustments. It's always bang on so I would not change to something different at this point.