Salinity refractometer or meter, which to believe

taricha

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I have a calibrated thermometer that I use to calibrate my other thermometers. :)

Or alternately, use a cheap swing-arm, because they are temp-self-correcting. :)
They are very tightly repeatable, so the measurement is however good the calibration solution was that I made (from Randy's article) to make my mark on the swing-arm.
 
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Skarpz1

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I use the digital scale and calibrate my refractometer with each use with distilled water. I use red sea coral pro, that gives stated weight for volume of water mixing ratio. I then cross check current salinity vs new water once Temps are the same with the same thermometer "hang on the glass El chepo thermometer" the most important is consistency pick 1 device for each task, complete each task the same way, always double check.
 

Randy Holmes-Farley

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I use the digital scale and calibrate my refractometer with each use with distilled water. I use red sea coral pro, that gives stated weight for volume of water mixing ratio. I then cross check current salinity vs new water once Temps are the same with the same thermometer "hang on the glass El chepo thermometer" the most important is consistency pick 1 device for each task, complete each task the same way, always double check.

Which refractometer?

For any except a true seawater refractometer, the use of distilled water is inherently always inaccurate for seawater salinity.

it is not just that it "might " be inaccurate. A perfectly made brine refractometer that is perfectly calibrated with DI water MUST be inaccurate by an exactly known amount.
 

denvereefroli

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Hi,
I'm new to the forum, but not new to saltwater/reef. Been away from saltwater for about 15 years.
I have 2 refractometers, a Hanna salinity meter and an old school float hydrometer. Both refractometers have been calibrated with 1.026 solution and distilled water. The meter has been calibrated with the proper cal solution.
Both refractometers are showing the salinity @ 1.027. The meter is showing 1.024 and 1.025 at times. The hydrometer shows just a hair over 1.025.

Which would you believe is correct?

I'm thinking that the 2 refractometers are correct.
Neither. Get a Tropic Marin Hydrometer.
 
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Randy Holmes-Farley

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Neither. Get a Tropic Marin Hydrometer.

How do you know it is accurate? Ever evaluate the calibration on yours?

This statement has, IMO, become super trendy to make these days, but I have rarely seen anyone actually verify their hydrometer accuracy.
 

Randy Holmes-Farley

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Because I have no idea what a conductivity meter is! :cool:

Refractometers measuring salinity by how much light bends travelling through it.

Conductivity meters measure salinity by how fast ions move in it in an electric field.

Neither is particularly intuitive. :)
 

Skarpz1

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Which refractometer?

For any except a true seawater refractometer, the use of distilled water is inherently always inaccurate for seawater salinity.
Inaccurate to a point I will agree 0 is much further from 1.024 but with cross match to the bucket and a known zero I'm okay with the inherent error window. Again it's more about consistency verses lab precise accuracy the corals will adjust to the unknown verible as long as it a stable unknown in my opinion.
 

Ocean’s Piece

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Randy Holmes-Farley

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Inaccurate to a point I will agree 0 is much further from 1.024 but with cross match to the bucket and a known zero I'm okay with the inherent error window. Again it's more about consistency verses lab precise accuracy the corals will adjust to the unknown verible asalong as it a stable unknown in my opinion.

It seems to me like throwing in the towel, but if you are OK being off by 1.7 ppt even when everything related to the measurement is perfect, then its a fine thing to do..

of course, if that cheap refractometer may not be perfectly made, all bets are off...
 
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Skarpz1

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It seems to me like throwing in the towel, but if you are OK being off by 1.7 ppt even when everything related to the measurement is perfect, then its a fine thing to do..

of course, if that cheap refractometer may not be perfectly made, all bets are off...
Okay, then what are you offering as a solution. Thousands of people run reefs just fine with refractometer, or hydrometer why over complicate a simple process to new users.
 

Randy Holmes-Farley

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That's a fine (although inconvenient) way to measure salinity, but unless you verify the calibration, you are just assuming it was made properly. You know what they say about people who assume...
 

Randy Holmes-Farley

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Kongar

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As a noob, I often see this “which one is correct” post and it baffles me.

I have a refractometer, and a little bottle of calibration solution from brs. I think it was called refracto juice or something silly.

Anyway, I take the refractometer, put three drops of solution on it and check the calibration. 95% of the time it’s dead on at 35, sometimes it’s off a little bit due to temp and I make a mental note. Then I wipe it and immediately check my water. It’s like the quickest test in the book and takes 15 seconds to check the cal.

what am I missing?
 

Randy Holmes-Farley

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As a noob, I often see this “which one is correct” post and it baffles me.

I have a refractometer, and a little bottle of calibration solution from brs. I think it was called refracto juice or something silly.

Anyway, I take the refractometer, put three drops of solution on it and check the calibration. 95% of the time it’s dead on at 35, sometimes it’s off a little bit due to temp and I make a mental note. Then I wipe it and immediately check my water. It’s like the quickest test in the book and takes 15 seconds to check the cal.

what am I missing?

Missing is the concern that some people have multiple bottles of calibration fluid and they do not always read the same. Also, multiple devices calibrated with the same fluids may not raed the same.

They can be mismade, evaporate, or be intentionally messed with before purchase (buy it, take out part and refill with any old water and return for a refund).
 
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Skarpz1

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So your solution to the simple question of how " I do the basic task of a safe water change" is to present a wall of text to a new user who has no idea of the basics of the tool they are using. You expect a new user to read understand and follow how to make and prepare home calibration fluid when the same beginner is struggling complete the basic task of salinity measurement.
You do you friend but I feel you may be speaking above the scope of the exp of the users who's ask these basic questions.
 

Skarpz1

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Glad you asked.

I have been "offering" a perfect DIY calibration solution for any type of conductivity device (including the Tropic Marin hydrometer) for many years:

Reef Aquarium Salinity: Homemade Calibration Standards by Randy Holmes-Farley - Reefkeeping.com
So your solution to the simple question of how " I do the basic task of a safe water change" is to present a wall of text to a new user who has no idea of the basics of the tool they are using. You expect a new user to read understand and follow how to make and prepare home calibration fluid when the same beginner is struggling complete the basic task of salinity measurement.
You do you friend but I feel you may be speaking above the scope of the exp of the users who's ask these basic questions
 

Randy Holmes-Farley

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So your solution to the simple question of how " I do the basic task of a safe water change" is to present a wall of text to a new user who has no idea of the basics of the tool they are using. You expect a new user to read understand and follow how to make and prepare home calibration fluid when the same beginner is struggling complete the basic task of salinity measurement.
You do you friend but I feel you may be speaking above the scope of the exp of the users who's ask these basic questions.

lol

Apparently, you are new here. Might want to read up first before criticizing that I am not helping enough.

I have more than 200,000 posts at reef chemistry forums helping new people how to handle all sorts of reef chemistry issues over the past 25 years.

A great many of those relate to salinity measurement and mismeasurement.

Mismeasurement is VERY common. It leads to all sorts of problems like why is my magnesium so low or so high. etc.

Getting salinity roughly correct can prevent a lot of pain.

I posted an article with an easy DIY to verify the accuracy of any device. It is VERY EASY if you read it. Did you, read it before blasting me?

You can also buy standards. its a fine way to go if you have confidence in the company. If not, you can make your own.
 

Skarpz1

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lol

Apparently, you are new here. Might want to read up first before criticizing that I am not helping enough.

I have more than 200,000 posts at reef chemistry forums helping new people how to handle all sorts of reef chemistry issues over the past 25 years.

A great many of those relate to salinity measurement and mismeasurement.

Mismeasurement is VERY common. It leads to all sorts of problems like why is my magnesium so low or so high. etc.

Getting salinity roughly correct can prevent a lot of pain.

I posted an article with an easy DIY to verify the accuracy of any device. It is VERY EASY if you read it. Did you, before blasting me? I doubt it. You didn't have time. Sad, really, that you do not have the courtesy to even read it before blasting me.

You can also buy standards. its a fine way to go if you have confidence in the company. If not, you can make your own.
No one is saying your not "helping enugh" no one is criticizing your knowledge. You probably know and have done more research then 90% of the internet. What I am saying is that you may be raising the basic knowledge bar no one is blasting you -you get your coffee yet?- yes you are correct in all your given facts but to a new person it's a bit overboard. You were the one who came on shooting everyone's process down before even mentioning your solution, you could have done it all in one post and moved on but no you decided to drag it out and yea I am new here what of it, do all new people have to pass threw your articles before being allowed to post? Was my information detrimental to the hobby did anyone's given information risk a tank? Take it easy dial it back a notch. Odd behavior for a moderator.
 

Kongar

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Missing is the concern that some people have multiple bottles of calibration fluid and they do not always read the same. Also, multiple devices calibrated with the same fluids may not raed the same.

They can be mismade, evaporate, or be intentionally messed with before purchase (buy it, take out part and refill with any old water and return for a refund).
Holy smokes! That’s a thing? What kind of a jerk would mess with calibration fluid? Some people…

I figured there might be differences in calibration fluids, and I wondered if they drifted between bottles/instruments/time. But I guess I always figured it would be close enough. 34-36 anything would work as long as it’s consistent. I guess I should pay just a little bit more attention to my salinity then I have been. Thanks for the help to all of us ;)
 
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