Ma877 calibration?

[Notsolostfish]

I ran out of the validation kit by milwaukee. What refractometer solution should i get to calibrate it?

 

[Randy Holmes-Farley Verified Community Expert]

It must be calibrated with pure fresh water, then I suggest checking it with a 35 ppt seawater refractometer standard.

 

[Gtinnel]

They recommend distilled water but I’ve used rodi water without issue.

 

[Notsolostfish]

It must be calibrated with pure fresh water, then I suggest checking it with a 35 ppt seawater refractometer standard.

So when i calibrate it with a 35ppt seawater i should be getting 35ppt? Or its going to range?

 

[Gtinnel]

So when i calibrate it with a 35ppt seawater i should be getting 35ppt? Or its going to range?

The Milwaukee digital refractometer is an exception because it has to be calibrated to zero with distilled (rodi) water not calibrated to 35ppt.
If you calibrate it with 35ppt water than your readings should be way off.

 

[Notsolostfish]

The Milwaukee digital refractometer is an exception because it has to be calibrated to zero with distilled (rodi) water not calibrated to 35ppt.
If you calibrate it with 35ppt water than your readings should be way off.

Im waiting on milwaukee to send me the validation kit and I’ll test again

 

[Notsolostfish]

The Milwaukee digital refractometer is an exception because it has to be calibrated to zero with distilled (rodi) water not calibrated to 35ppt.
If you calibrate it with 35ppt water than your readings should be way off.

So basically it comes down to how good the solution u use. The refractometer solution

 

[Randy Holmes-Farley Verified Community Expert]

They recommend distilled water but I’ve used rodi water without issue.

That difference won't matter.

 

[Randy Holmes-Farley Verified Community Expert]

So when i calibrate it with a 35ppt seawater i should be getting 35ppt? Or its going to range?

Calibrate with fresh water, then confirm a proper reading with a 35 ppt standard, which should read 35 ppt. if it is off (say, 33 or 34), and you have confidence in the 35 ppt standard, then I'd manually correct all readings by adding 2 or 1 ppt, respectively.

I don't see any reason to buy fresh water from Milwaukee for calibration, if that's all you are getting in the "kit".

 

[Notsolostfish]

Calibrate with fresh water, then confirm a proper reading with a 35 ppt standard, which should read 35 ppt. if it is off (say, 33 or 34), and you have confidence in the 35 ppt standard, then I'd manually correct all readings by adding 2 or 1 ppt, respectively.

I don't see any reason to buy fresh water from Milwaukee for calibration, if that's all you are getting in the "kit".

I wish theres a video explaining how you do your 35ppt saltwater. English is not my first language, and im not really a DIY savvy. To create your salt.

 

[Randy Holmes-Farley Verified Community Expert]

I wish theres a video explaining how you do your 35ppt saltwater. English is not my first language, and im not really a DIY savvy. To create your salt.

No video, but its simple enough if you have a scale and table salt (sodium chloride):

Refractometers and Salinity Measurement - REEFEDITION

Title photo by R2R member Rskillz By Randy Holmes-Farley Salinity is one of the most important parameters measured in reef aquaria. It controls not only the salt balance between an organism and its surrounding environment, but also the levels of a host of ions Read more here...

www.reefedition.com

To provide a standard for refractometers requires a solution whose refractive index is similar to normal seawater. Seawater with a salinity of 35 ppt has a refractive index of 1.3394. Likewise, the refractive index of different sodium chloride solutions can be found in the scientific literature. My CRC Handbook of Chemistry and Physics (57th Edition, Page D-252) has such a table. That table has entries for 3.6 and 3.7 weight percent solutions of sodium chloride that span the value for normal seawater. Interpolating between these data points suggests that a solution of 3.65 weight percent sodium chloride has the same refractive index as 35 ppt seawater, and therefore can be used as an appropriate standard (Table 5).

This 3.65 weight percent sodium chloride solution can be made by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified freshwater. This recipe can be scaled to any appropriate size if suitable instruments are available (36.5 grams in 963.5 grams (mL) of water, 0.365 grams in 9.635 g (mL) of water, etc.).

 

[Notsolostfish]

No video, but its simple enough if you have a scale and table salt (sodium chloride):

Refractometers and Salinity Measurement - REEFEDITION

Title photo by R2R member Rskillz By Randy Holmes-Farley Salinity is one of the most important parameters measured in reef aquaria. It controls not only the salt balance between an organism and its surrounding environment, but also the levels of a host of ions Read more here...

www.reefedition.com

To provide a standard for refractometers requires a solution whose refractive index is similar to normal seawater. Seawater with a salinity of 35 ppt has a refractive index of 1.3394. Likewise, the refractive index of different sodium chloride solutions can be found in the scientific literature. My CRC Handbook of Chemistry and Physics (57th Edition, Page D-252) has such a table. That table has entries for 3.6 and 3.7 weight percent solutions of sodium chloride that span the value for normal seawater. Interpolating between these data points suggests that a solution of 3.65 weight percent sodium chloride has the same refractive index as 35 ppt seawater, and therefore can be used as an appropriate standard (Table 5).

This 3.65 weight percent sodium chloride solution can be made by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified freshwater. This recipe can be scaled to any appropriate size if suitable instruments are available (36.5 grams in 963.5 grams (mL) of water, 0.365 grams in 9.635 g (mL) of water, etc.).

My kitchen scale doesnt measure .1.. it only measurured 9ml 10 ml.. etc

 

[Gtinnel]

My kitchen scale doesnt measure .1.. it only measurured 9ml 10 ml.. etc

You could always scale the mixture up to a large amount and use 365 grams of salt and 9635 ml of water. It would still cost almost nothing to make since table salt is cheap and then you’ll have a few gallons of testing solution.

Scaling the solution up makes small measuring errors insignificant.

More realistically you could double the larger values that Randy quoted and use 73g of table salt and 1927 ml of rodi water and you wouldn’t have to deal with fractional amounts.

 

[Notsolostfish]

You could always scale the mixture up to a large amount and use 365 grams of salt and 9635 ml of water. It would still cost almost nothing to make since table salt is cheap and then you’ll have a few gallons of testing solution.

Scaling the solution up makes small measuring errors insignificant.

More realistically you could double the larger values that Randy quoted and use 73g of table salt and 1927 ml of rodi water and you wouldn’t have to deal with fractional amounts.

You could always scale the mixture up to a large amount and use 365 grams of salt and 9635 ml of water. It would still cost almost nothing to make since table salt is cheap and then you’ll have a few gallons of testing solution.

Scaling the solution up makes small measuring errors insignificant.

More realistically you could double the larger values that Randy quoted and use 73g of table salt and 1927 ml of rodi water and you wouldn’t have to deal with fractional amounts.

Any morton salt would work?

 

[Gtinnel]

Any morton salt would work?

I used Morton’s Iodized salt. I don’t know if being Iodized matters but I know in his article Randy specifically said Morton’s Iodized salt so that’s what I used.

 

[Notsolostfish]

I used Morton’s Iodized salt. I don’t know if being Iodized matters but I know in his article Randy specifically said Morton’s Iodized salt so that’s what I used.

So its that easy. Measure 1927 of water in a gallon or something and add 72g of iodized salt? And boom i have a 35ppt ready ?

 

[Gtinnel]

So its that easy. Measure 1927 of water in a gallon or something and add 72g of iodized salt? And boom i have a 35ppt ready ?

It’s 73g of iodized salt and use rodi water, but yes it’s that easy. Just make sure it’s thoroughly dissolved. It’s crazy what people pay for small bottles of solution that essentially cost nothing to make.

Please be aware this is the solution is for a refractometer (which the Milwaukee is). For science reasons that I will never understand the solution for a conductive salinity tester uses a different “recipe”. Also, just to make sure it’s clear do not use this solution to calibrate your Milwaukee, just use it to make sure it reads correctly after calibrating with distilled or rodi water.

 

[Notsolostfish]

It’s 73g of iodized salt and use rodi water, but yes it’s that easy. Just make sure it’s thoroughly dissolved. It’s crazy what people pay for small bottles of solution that essentially cost nothing to make.

Please be aware this is the solution is for a refractometer (which the Milwaukee is). For science reasons that I will never understand the solution for a conductive salinity tester uses a different “recipe”. Also, just to make sure it’s clear do not use this solution to calibrate your Milwaukee, just use it to make sure it reads correctly after calibrating with distilled or rodi water.

I did it at first i got 1.026 then waited a min later and its 1.027 im confused

 

[Notsolostfish]

It’s 73g of iodized salt and use rodi water, but yes it’s that easy. Just make sure it’s thoroughly dissolved. It’s crazy what people pay for small bottles of solution that essentially cost nothing to make.

Please be aware this is the solution is for a refractometer (which the Milwaukee is). For science reasons that I will never understand the solution for a conductive salinity tester uses a different “recipe”. Also, just to make sure it’s clear do not use this solution to calibrate your Milwaukee, just use it to make sure it reads correctly after calibrating with distilled or rodi water.

I tried another batch. And i got 1.027 this time. Im pretty positive its related that i cant see after the decimal point on my scale. Im probably getting 73.5g or 73.8 but i cant see it and its affecting my reading. I guess ill have to buy more refractometer solution.

 

[Gtinnel]

I tried another batch. And i got 1.027 this time. Im pretty positive its related that i cant see after the decimal point on my scale. Im probably getting 73.5g or 73.8 but i cant see it and its affecting my reading. I guess ill have to buy more refractometer solution.

The “recipe” is to make 35ppt solution which is 1.0264. So 1.026 or 1.027 are exactly what you would want to see and easily within the accuracy of the MA887. What specific gravity were you expecting? Also you can change the readout on the Milwaukee to ppt and see what it gives.