digital vs naked eye you decide
 

We recently started looking into developing another Aqua Digital product - a hand held digital refractometer using conductivity instead of prism.

The fore and against we see as this

the Fore - easy to read, highly accurate
the against - needs calibrating everytime, although a one touch event.
Peoples built in feeling nothing is better than a refractometer

Ok to pick up on this argument - How many out there really are aware 99% of refractometers are designed to read NACL not NSW? The difference being NACL has no impurities or added minerals that throw out the reading, this is why unless you have a dedicated NSW refractometer, they must be calibrated to a known and trust NSW solution such as pinpoints. Through support we come across a massive amount of lack of education in this.

The concern is how many do not do this and have innacurate salinity readings in their tank? This is the biggest support question we get when clients install expensive salinity probes from GHL and get a different reading, and the reason we are considering the digital approach.

So my question to the community is this - Would you trust a digital reader that can only read what is the correct salinity even if it differs from you old NACL refractometer. Or would we get multiple support argumetns over the reading from what people have learned to accept as correct (when on most cases it is not)

We would love to bring these to market but feel that the hobby is too biased towards what has become standard.

Your feedback is important.

I wasn't aware that our refractometer looked at a different compound

Most Refracts are designed for NACL we are only interested in NSW, this is only an issue with prism refractometers.

Refractometers read by light refraction and this refraction is read by a scale on the glass.

Digital read the conductance of the water thus not effected by impurities or minerals so as accurate whether NSW or NACL

First of all, if it no longer involves prizms, it will no longer be a refractometer IMO. It will then be a conductivity meter.
Randy Holmes-Farley has many articles explaining that the standard refractometer is only accurate for NaCl, or, when calibrated with a calibration fluid, only accurate at that specific range.
It's amazing how many people with a standard refractometer swear up and down that their refractometer is accurate with using water to calibrate as well as using calibration fluid. The only way this is possible is when using a seawater refractometer.
Randy on Refractometers and Salinity
This is his Archived Article on using Conductivity to Measure Salinity
Randy on Home Made Calibration Standards Including Conductivity

All that being said, I still use my SeaTest swing arm hydrometers that I started with over 18 years ago. I check them about once a year against my certified calibrated hydrometer from Fisher Scientific and it is always on.
I rinse after every use and soak overnight in vinegar once a week.

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.

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.

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

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.

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?

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.

With the traditional refractometers how much of an error factor are we talking about nacl - NSW

I have seen readings as far out as 5mS and more, it varies depending depending on the mineral content of the (wrong) solution you have used.

Well if you're using a calibration solution for a digital meter anyway then you can certainly do the same for a refractometer. No matter what kind of refractometer you have if you calibrate with a NSW solution at the same range you keep your tank then you will have no accuracy issues and you don't have to calibrate it every time you use it. You really can't say this digital meter will be more accurate, that's just not accurate information and unethical marketing. All you can say is that rather having to read a gauge you get a digital read out which to me seems hardly worth while as refractometers are very easy to read.

Erm??? Not quite sure why you are getting upset over this, the thread is asking for users input in a new product and its viability, nobody is marketing anything. We are asking for feedback of a potential new product not askiing you to believe some marketing hype.

That being said, a prism refractometer is only as accurate as its calibration (same as a digital unit) however there is no risk of human miss read error with digital.

I am looking for balanced debate for and against nothing more, in other words what would make people switch?

Based on everyones feedback that is relevant to the original question we can then decide the market potential of this product.

I'm not debating marketing or getting upset, just stating I don't see any valuable gains to such a product and my reasons why as per your request. I wasn't stating you were being unethical or marketing the product but it seems the main advantage here is accuracy and not convenience however it should be clear that the gained accuracy is from human error alone not that refractometers are inaccurate which is a conclusion people tend to make whether it was stated exactly that way or not. That's all I wanted to say, there are many similar products out there now and all being marketed with the claim our refractometers aren't accurate which is just isn't true. If I'm given the opportunity to stop another product from making such claims I will do so.

Even if the reading is a few points out does it really matter??.. Using the same testing tool, match tank water with new water change water, adjust if needed and add to tank... I would never by a digital ...... hand grenade and horse shoes.

Exactly however unlike other testing equipment refractrometers don't require the hopeless attempt of matching a color to another set that all look the same :lol: So digital kits like Hanna are quite valuable and are not overly more expensive. A typical refractometer costs around $60 and IMO are easy to read, the difference between blue and white is noticeable and the line is very defined. So the question is how much more does one have to pay to eliminate the so called difficult task of reading a refractometer?

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.

we estimate based on us in charge of manufacture about $45.00

The pro to this in our view is

Easy of calibration no requirement to find a good NSW solution
Ease of reading.

If the pricing is similar to a good refractometer and I didn't already have one I would probably go with a digital one, but I wouldn't replace my refractometer with one just because.

Everyone's head is pointy enough already, why make it worse with a new gadget. :lol:

I would agree with ease of reading but that's about it. Despite the fact it won't require a specific kind of calibration fluid you will still need a verified fluid so that's really a moot point. Price sounds compatible which is good but really what will kill this product is the constant need for calibration, unless you can insure reasonable accuracy using RO water for calibration fluid it's ultimately doomed to fail. A hobbyist will always need a supply of calibration fluid, if it is lost, spilled or contaminated the meter is useless until more fluid can be purchased. For something that is typically used all the time, often in emergency situations it just doesn't sound reliable enough.

This is all good feedback, we always like to involve our target audience with product development, its a great barometer for us.

In regards to calibrating, I say everytime to ensure the best of readings even Hanna meters require this, and to be honest I would not even trust a refractometer unless it has been calibrated before hand, but thats personal choice.

A digital meter does not require pre use calibration its more a recommendation for optimum accuracy, just as with a refractometer and also the likes of hanna or pinpoint.

I think it's a neat idea. I was silly and bought my refractometer without a light not to mention I have to take my glasses off to squint at it aside from finding a light to point it at. If it's easier to use (not all of us are reef gear heads) and priced the same as a traditional vertex style. I'd be interested.
Anything that makes it easier for me to keep my fish happy is a good investment.

Great input, thanks this all helps.

Thankfully I dont have bad eyesight, so reading a refractometer isnt an issue I personally have to deal with.
But for those that wear glasses this might be a seller.

I'll stick with my vertex refractometer for the following reasons:
-It's a simple design
-No batteries required
-No need to calibrate every time
-Tough

If this unit was priced identically to a standard refractometer I'd still buy the refractometer.

While I've never heard or calibrating a refractometer prior to every use if such a new digital device would prove as reliable without the "every use calibration" it would certainly change things and be a very useful device but like everything newly adapted for this hobby reliability has to be earned :wink:

I may get some prototypes sent across and hand out for free to those that have participated above my post here.

watch this space ;)

This could potentially be a good item if it was reasonably priced, I say this as I have quite a few elderly customers and they find it a pita to read the refractometer, solution or not they would probably go for a digital....

Steve

[quote=Ross;721127]Thankfully I dont have bad eyesight, so reading a refractometer isnt an issue I personally have to deal with.
But for those that wear glasses this might be a seller.
QUOTE]

I wear glasses but to read a refractometer I just take them off. The image is only 1/2" away from your eye and most have focus adjustment anyway.

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

Would these digital one be temperature compensated

ALL digital have to be ATC they will not work in any accurate level without.

I like the idea. My vision is not what it was and sometimes have difficulty seeing the exact measurement in my refractometer.