Calibrating a refractometer with distilled water?

[Solo McReefer]

Large hydrometers always broke on me too easy, in the past

I will look at your recommendation

 

[BeanAnimal]

Large hydrometers always broke on me too easy, in the past

I will look at your recommendation

You certainly do have to be careful. But IMHO for the price and accuracy they can’t be beat.

 

[drolmaeye]

You have used it a fair bit, but in reference to what standard? itself?

The argument to calibrate close to the measure is to ensure accurate measurement, there is no need for a “universal” calibration unless you plan to measure over a wide range. That is the point.

I measure salinity in my DT at 77-78 F using a Tropic Marin hydrometer, then I zero my Milwaukee using RO/DI water, then I measure salinity of the same sample water using my Milwaukee digital refractometer. The result I repeatably get is 36 ppt (although I would expect 35 ppt). I then routinely check aquaria and mixing station with the Milwaukee refractometer shooting for 36 ppt, and regularly (every three months or so), repeat the Tropic Marin hydrometer exercise.

My thumbs don't have the stamina to explain why a manufacturer might use 0 ppt as a reference rather than 35 ppt, but I would ask you to reflect a bit and see if you could understand (if not also agree).

As for using the term "garbage" in conjunction with that product, I still disagree.

 

[Solo McReefer]

Milwaukee makes pH monitors and controllers

The analog would be for those to 'calibrate' a 7.0pH solution(zero), and have no other reference points to calibrate off of

 

[drolmaeye]

Milwaukee makes pH monitors and controllers

The analog would be for those to 'calibrate' a 7.0pH solution(zero), and have no other reference points to calibrate off of

So, a couple of things:

1. apples and oranges.

2. A pH of 7.0 is analogous to a salinity of 0 ppt or a conductivity of near zero. What would the 35 ppt equivalent of pH be? 8.3? And who makes the standard? These are real problems for manufacturers.

 

[Solo McReefer]

You have obviously have no experience calibrating a pH probe

If I zero a weight scale to zero

That is NOT calibration

That is zeroing

There are at least 2 points for pH probe calibration, sometimes 3 or more. Yes, 7.0 would be zeroing the pH probe, not calibration. Having a point higher and lower are required

How about those apples?

Orange you glad you know this now?

 

[drolmaeye]

You have obviously have no experience calibrating a pH probe

If I zero a weight scale to zero

That is NOT calibration

That is zeroing

There are at least 2 points for pH probe calibration, sometimes 3 or more. Yes, 7.0 would be zeroing the pH probe, not calibration. Having a point higher and lower are required

How about those apples?

Orange you glad you know this now?

It's not that I have no experience calibrating a pH probe (I have several pH probes in my palace and use solutions at 4, 7, 9.18, and 10 to calibrate them, depending on the manufacturer's instructions), I'm only trying to say that a refractometer calibration is not completely analogous to a pH probe calibration. Maybe my "apples and oranges" was a bit over the top (but I don't think so).

Let me get back to the two things I wanted to point out in my original reply:

1. The Milwaukee 887 is not garbage. (ETA it can serve as a solid piece of equipment in the reefer's toolbox,)
2. While I certainly understand calibration at or near the expected measurement value, I also understand the manufacturer's choice to use 0 ppt as a reference.

 

[Solo McReefer]

Why are you quoting me?

Seems your issues are mostly with what Bean Animal writes

I see zero value in calling a zero, calibration

You will not convince me otherwise, even from the balcony of your palace, M'Lord

 

[drolmaeye]

Why are you quoting me?

Seems your issues are mostly with what Bean Animal writes

I see zero value in calling a zero, calibration

You will not convince me otherwise, even from the balcony of your palace, M'Lord

I'm quoting you because since post 24 it has been a polite, interesting (and as a bonus, fruity) exchange between the two of us. It's not that I have an issue with anyone, It's really just that the topic is interesting to me and I think the discussion is helpful.

As I have mentioned a number of times already in this thread, I absolutely understand the idea of referencing or calibrating a measurement device close to the expected measurement, I've just tried to argue the fact that a manufacturer might have reasons for choosing a different value.

In an earlier post you mentioned you purchased as many as three reference solutions at 35PPT and they were all giving you different results. A manufacturer might understand that this could be an issue, and even believe that the idea of producing water at 0 ppt is a more reliable, repeatable standard. I could go out tomorrow morning to target, to Walmart, to my local grocery store, and get distilled water that should be 0TDS/ppt. In the long run, for the majority of users, this convenience of referencing off of a reliable and widely available reference solution may outweigh the benefits of referencing or calibrating against a 35PPT solution.

Edit: removed text that did not add to discussion.

 

[Solo McReefer]

Too long post

Deleted