digital vs naked eye you decide

[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.