digital vs naked eye you decide

[sphelps]

Personally I think such a device would be a waist of money.

1 - I'm yet to meet anyone overly concerned regarding inaccurate salinity levels in their tank if they are already using a refractometer.

2 - Anyone overly concerned regarding inaccuracy of an NACL refractometer only needs to calibrate it once using natural seawater to verify it's accuracy. Once verified or even adjusted if it is way out the meter is now completely accurate.

3 - In my own personal testing my refractometer measures natural seawater perfectly accurate even calibrated with RO water. I've had this meter for years, it was over expensive ($50) and referred to as salinity refractometer.

4 - The resent outburst of concern regarding inaccurate refractometers seems more of a myth (exaggerated from fact) and now many companies are releasing new seawater refractometers, some digital some not but always with the promise of more accuracy and a significantly higher price tag. It just seems more of a marketing ploy to me.

5 - The only reason I would spend more on a digital device is if it would make things easier. However refractometers are already very easy and just the fact that you would have to calibrate it every time is enough to dismiss any gain from accuracy which I don't even believe is there. Conductivity meters are also prone to many errors as well, more so than a standard refractometer.

[Cal_stir]

Originally Posted by sphelps

Personally I think such a device would be a waist of money.

1 - I'm yet to meet anyone overly concerned regarding inaccurate salinity levels in their tank if they are already using a refractometer.

2 - Anyone overly concerned regarding inaccuracy of an NACL refractometer only needs to calibrate it once using natural seawater to verify it's accuracy. Once verified or even adjusted if it is way out the meter is now completely accurate.

3 - In my own personal testing my refractometer measures natural seawater perfectly accurate even calibrated with RO water. I've had this meter for years, it was over expensive ($50) and referred to as salinity refractometer.

4 - The resent outburst of concern regarding inaccurate refractometers seems more of a myth (exaggerated from fact) and now many companies are releasing new seawater refractometers, some digital some not but always with the promise of more accuracy and a significantly higher price tag. It just seems more of a marketing ploy to me.

5 - The only reason I would spend more on a digital device is if it would make things easier. However refractometers are already very easy and just the fact that you would have to calibrate it every time is enough to dismiss any gain from accuracy which I don't even believe is there. Conductivity meters are also prone to many errors as well, more so than a standard refractometer.

+1, if my refractometer is out 1/10 of 1 point, so what, everybody runs their systems at a different salinity, there is even variations in different areas of different oceans, the main thing is that they are consistant, big deal if i think my salinity is 1.025 but it is actually 1.024, as long as it is consistant.

[Aqua-Digital]

REMEMBER - This thread is driven by your input, not me trying to sell you something else, its here for us to gauge viability of a new product.

My only sub point on this is the highlight that a refractomer should be calibrated to NSW, but thats a sub argument to the main point of the thread.

[sphelps]

So in regards to calibrating this digital meter, what is used for a fluid?

[Aqua-Digital]

As its digital and does not rely on a refractive index you can use any known value saline solution that is in tolerence with the ppm value the meter is designed to be calibrated to.

This is the difference of refractive vS digital, digital is not bothered about water pollutants that can throw off a refractive index, this is why you can use either NSW or NACL with them and why they are more accepted in laboratories for better accuracy.

You cna get digital refractive such as Hanna, this is basically an auto refractive refractometer, but works on the same principle as a refractometer. This is why you have to state iif you want it for marine or chemical use when purchasing.

Calibrating a digital is simple - place in solution - hold down button - wait a few seconds - calibrated.

[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.

[rayjay]

Originally Posted by sphelps

4 - The resent outburst of concern regarding inaccurate refractometers seems more of a myth (exaggerated from fact) and now many companies are releasing new seawater refractometers, some digital some not but always with the promise of more accuracy and a significantly higher price tag. It just seems more of a marketing ploy to me.

Is this comment based on any documented evidence or just your personal experience along with the few others that have reported the same?
At least for the point of view that a seawater and a NaCl refractometer produce different results, there is documentation out there, and the fact that Dr Randy Holmes-Farley confirms that it is different, then that is more convincing to me than a hobbyist's anecdotes.
Randy has tested many refractometers and found errant results from many so those particular ones are only accurate at the range they are calibrated for.
This can be true even for seawater refractometers. Generally, but not exclusively, the higher priced ones will be more likely to be more accurate.
Maybe your refractometer is an errant NaCl refractometer that just lucked in to be errant in a way as to be accurate through the range. Like I said before though, it's impossible for an NaCl refractometer and a seawater refractometer with true prisms respectively, to give the same results throughout the scale even if both are calibrated with the same calibration fluid. The refracting prisms in each case are different.
The shortest explanation of how they work should suffice and can be found at Refractometry Theory and Abbe Refractometer
Also, while inaccuracies can exist in conductivity meters as well as refractometers, science basically uses conductivity over refraction as they prove to be more reliably accurate.

This link is merely an "interest" link some might find interesting, especially if they teach school. Refractometer

[Mike-fish]

Would these digital one be temperature compensated