Refractometer Recalibration

[stdreb27]

Originally Posted by saltygerman
http:///forum/post/2903019
Ok being as I always have to overthink things...here we go. I just got my RO/DI unit I also have a water softener. Will the salt in my water supply throw off my Refractor calibration or does the RO/DI filter all this out?

RO water, or heck from tap you aren't going to see the difference with your neeked eye.
Originally Posted by alh
http:///forum/post/2903042
My city water is so bad (600+ TDS) that I am lucky to get my RODI water to about 4, give or take. Being fussy, I didn't want to use that water for calibration so I bought salinity calibration fluid.
That is really bad for city water, in texas i think tds has to be below 400.

 

[fishytim]

Just go buy a gallon of distilled water at the grocery store for $1........calibrate it to 0 and you're good to go.....

 

[bang guy]

Originally Posted by florida joe
http:///forum/post/2903094
Not so sure Bang, the temperature of your water is not relevant if you have a refractometer with temperature compensation. (Which most are). If as you say the refractometer was calibrated at 68 f and I had distilled water at 68 f it should read zero. If not recalibration is called for Is it not easier to bring the water to 68 f then the refractometer?

It is much much easier to get water to 68F instead of the refractometer.
However, if the refratometer is at 90F because you store it on top of the canopy and you chill the water to 68F before you use the refratometer, what happens when you place two drops of 68F water on a thick piece of glass surrounded by aluminum that's at 90F?
IMO the water will quickly warm up to 90F as the heat transfers from the glass to the water. That's what ATC refractometers are designed to do. This is why, IMO the water temp is irrelevant and refractometers should probably be calibrated at room temp, the same temp you will be using them at.

 

[locoyo386]

Hi there,
Just wanted to say that refractometer (handheld analog type) measure a liquid's refractive index. From this value the specific gravity of fluids can be obtained, with the temperature of the fluid being a factor (temperature dependent). That is why I think that the salinity scale ones that are used, for this hobby, are typically already calibrated for saltwater and have automatic temperature compensation (not dependent on temperature of the fluid being tested). I know they have some that can measure the sugar level just as these measure the salinity level. But you would not use the scale of one to mesure the level of the other.
Originally Posted by Bang Guy
http:///forum/post/2903073
Hey there Crazy Joe

The temperature of the water being tested isn't relevant. What you actually need to do if you want to calibrate at 68F is get the temperature of the refractometer to 68, not the test water. I believe it is advisable to test using the device at room temp though.
The ideal calibration would be to use 35ppt calibration fluid with the refractometer at the temperature it would normally be when testing your tank water. I caution against storing the refractometer near a heat source because the reading will be unpredictible. For example, I have seen quite a few people store their refracometer on top of a hot canopy.
As far as Salinity of RO being zero, this is absolutely true. I just want to mention that some hobbiests incorrectly use the S.G. scale and that side would read 1.00 with RO water. You are correct in that since Refractometers do not measure Specific Gravity it is the Salinity scale that should be used "0/000".

 

[bang guy]

Originally Posted by locoyo386
http:///forum/post/2903239
Hi there,
Just wanted to say that refractometer (handheld analog type) measure a liquid's refractive index. From this value the specific gravity of fluids can be obtained, with the temperature of the fluid being a factor (temperature dependent). That is why I think that the salinity scale ones that are used, for this hobby, are typically already calibrated for saltwater and have automatic temperature compensation (not dependent on temperature of the fluid being tested). I know they have some that can measure the sugar level just as these measure the salinity level. But you would not use the scale of one to mesure the level of the other.
There is a BRIX conversion but I don't remember the formula.

 

[locoyo386]

Is this the one?
http://www.jencointernational.com/brix_convert.htm
Originally Posted by Bang Guy
http:///forum/post/2903287
There is a BRIX conversion but I don't remember the formula.

 

[florida joe]

Originally Posted by Bang Guy
http:///forum/post/2903220
It is much much easier to get water to 68F instead of the refractometer.
However, if the refratometer is at 90F because you store it on top of the canopy and you chill the water to 68F before you use the refratometer, what happens when you place two drops of 68F water on a thick piece of glass surrounded by aluminum that's at 90F?
IMO the water will quickly warm up to 90F as the heat transfers from the glass to the water. That's what ATC refractometers are designed to do. This is why, IMO the water temp is irrelevant and refractometers should probably be calibrated at room temp, the same temp you will be using them at.
I totally agree. So my question to you is this. If my ambient temp is 76 f and my tank temp is 79 f and it’s a given that refractometer are calibrated at 68 f. Would I not get a more accurate calibration if i could get both the refractometer and water to 68f and if that is the case even lowering one is helping the cause
My friend you know me by now “never give up the fight”

 

[bang guy]

Originally Posted by florida joe
http:///forum/post/2903372
I totally agree. So my question to you is this. If my ambient temp is 76 f and my tank temp is 79 f and it’s a given that refractometer are calibrated at 68 f. Would I not get a more accurate calibration if i could get both the refractometer and water to 68f and if that is the case even lowering one is helping the cause
My friend you know me by now “never give up the fight”

I believe you are right. If everything is at the precise temp that the refractometer is calibrated at you have better odds of getting a perfect reading.
How much will it matter if you drop tank water on the refractometer at room temp and you have an error rate of 2%?

 

[florida joe]

Originally Posted by Bang Guy
http:///forum/post/2903444
I believe you are right. If everything is at the precise temp that the refractometer is calibrated at you have better odds of getting a perfect reading.
How much will it matter if you drop tank water on the refractometer at room temp and you have an error rate of 2%?
I am guessing none at all. If you look out your window to the south east you will see a white flag

 

[bang guy]

Originally Posted by florida joe
http:///forum/post/2903454
I am guessing none at all. If you look out your window to the south east you will see a white flag

You gave up too soon Joe! I was about to concede.
Let's call it a tie and a complete understanding.

 

[florida joe]

Originally Posted by Bang Guy
http:///forum/post/2903492
You gave up too soon Joe! I was about to concede.
Let's call it a tie and a complete understanding.
As a chess player I must prefer to call it a draw. So my hand goes out to you. I would have thought our little debate would have had more people participating though. I guess your reputation was factored in.