BRS refractometer

[JCulmo]

Hi
Been having all sorts of conflicting info regarding calibrating refractometers. I have one that's 5 years old and the hinge is half broken. Directions state to cal with RO water at 1.000
Have the digital Milwaukee meter but it has never read the 35 ppt. Correctly. It's always off by 2 points so that gives me cause for concern
Today I ordered the BRS refractometer with the cal solution.
So the question is: Is this a seawater or saltwater refractometer? I'm presuming that using the 35 ppt cal solution will get me where I need to be so that I can trust something....
Currently tank looks good and everyone is alive so that's a plus.
My old refractometer reads 1.0235. Digital reads 1.025 so I'm in the ballpark but I want to be exact. Too much invested in this to be guessing
Any advise would be greatly appreciated

 

[disc1]

Take the seawater calibration solution and put it on there. Set to whatever line or number you like. Make your water match that and you know you're good no matter what type of refrac it is.

 

[JCulmo]

Take the seawater calibration solution and put it on there. Set to whatever line or number you like. Make your water match that and you know you're good no matter what type of refrac it is.

That's a new approach that I haven't read before but I love it

 

[disc1]

Sure you have. That is how single point calibration works. You can use rodi and set it to 0 or something and you will always have something to match rodi to. If you want to measure something ( with any instrument ) very far away from a calibration point then you need two calibration points. Unfortunately that isn't really an option with a refractometer.

 

[JCulmo]

I hear what you are saying and I do understand it. However on my previous calibrated refractometer when I calibrate to the known cal solution of 35 ppt and then add rodi water after cleaning off the cal solution my readings are always lower than the 1.000 line. That's most likely due to the span of the range. So it's best to calibrate where my expected readings will be which is in the 1.026 range?

 

[dkeller_nc]

Were I you, I'd get you Milwaukee digital refractometer fixed (if it is indeed broken/miscalibrated). They're remarkably easy to use, if if setup correctly at the factory, highly accurate.

Here's a couple of points - your calibration solution needs to be a refractometer calibration solution. The measurement cell on the Milwaukee must be clean, and the battery must be reasonably fresh. A pure RODI solution should read 1.000. If not, the cell needs to be cleaned and/or the instrument needs to be zeroed.

Then check your cal solution. It should be at the same temp as the Milwaukee refractometer (you may need to put both the instrument and cal solution in your aquarium cabinet for 20 to 30 minutes to make sure).

If it's still "off" by 0.002 sp. gr., call Milwaukee. They may warrant a replacement instrument, or a return to the factory for re-cal.

By the way - do not store the Milwaukee or any other electronic instrument in your aquarium cabinet; the humid salty air will trash it in very little time.

 

[JCulmo]

Were I you, I'd get you Milwaukee digital refractometer fixed (if it is indeed broken/miscalibrated). They're remarkably easy to use, if if setup correctly at the factory, highly accurate.



Here's a couple of points - your calibration solution needs to be a refractometer calibration solution. The measurement cell on the Milwaukee must be clean, and the battery must be reasonably fresh. A pure RODI solution should read 1.000. If not, the cell needs to be cleaned and/or the instrument needs to be zeroed.



Then check your cal solution. It should be at the same temp as the Milwaukee refractometer (you may need to put both the instrument and cal solution in your aquarium cabinet for 20 to 30 minutes to make sure).



If it's still "off" by 0.002 sp. gr., call Milwaukee. They may warrant a replacement instrument, or a return to the factory for re-cal.



By the way - do not store the Milwaukee or any other electronic instrument in your aquarium cabinet; the humid salty air will trash it in very little time.

I have been in contact with Milwaukee tech support. They provided some info on getting a true zero cal. I did as stated but it still reads 37 on a know good 35 ppt solution. I believe we are almost at the point of returning it or getting a replacement. I do love the Milwaukee for several reason and hope it can fixed to the point that I trust it and can use it.
I have been making sure that the Milwaukee, cal solution and test sample are all at the same temp so I'm not sure what else to do. Hoping tech support can take it back fix it and get it back to me.
For now I'll work with a calibrated refractometer using 35 or 1.026 solution and go from there. [emoji4]

 

[disc1]

I hear what you are saying and I do understand it. However on my previous calibrated refractometer when I calibrate to the known cal solution of 35 ppt and then add rodi water after cleaning off the cal solution my readings are always lower than the 1.000 line. That's most likely due to the span of the range. So it's best to calibrate where my expected readings will be which is in the 1.026 range?

Yes, that's how single point calibration works. It only calibrates the instrument at one point. If you're willing to take your readings and do the math you could use both readings to create a calibration curve and use the entire scale.

And yes it is best to calibrate to a number as close to what you intend to measure as possible.

 

[JCulmo]

Yes, that's how single point calibration works. It only calibrates the instrument at one point. If you're willing to take your readings and do the math you could use both readings to create a calibration curve and use the entire scale.



And yes it is best to calibrate to a number as close to what you intend to measure as possible.

Thank you for the in depth clarification

 

[salty joe]

I'd like to add that it's a good idea to occasionally check your refractometer. Two months after getting mine it needed another calibration. Six months later and it seems to be solid, but I still check it.

 

[Mrs. Music]

Take the seawater calibration solution and put it on there. Set to whatever line or number you like. Make your water match that and you know you're good no matter what type of refrac it is.

Oh my gosh. You mean use the calibration solution but set it to the number line that is easiest to see? And then always match the new make up water to that setting?

 

[disc1]

Oh my gosh. You mean use the calibration solution but set it to the number line that is easiest to see? And then always match the new make up water to that setting?

If all you are interested in is matching up your salinity that would be fine. On many refractometers that aren't graduated for seawater or saltwater that's about the best you'll ever do. If you calibrate to the 35ppt mark you can have some confidence in the numbers close by, so it makes it a little easier to see how far off you are if you use the right line. But for just matching salinity it doesn't matter.

Most of the time what I do is to take a reading from my tank water and then match my change water to that. I have a high level of confidence that my tank isn't going to be way off the mark. Once in a while I'll actually calibrate the refrac and check to see if the tank is still good. But for the most part I just want the change water to match the tank.

 

[Mrs. Music]

My BRS refractometer does not show the 35ppt mark well. The 30 is nice and bold, which I have always felt was just dumb. It is just annoying, and I have to remove my glasses to see it well. Thanks. I might give this a try.

 

[Buzz1329]

Of the three brands I've tried, The BRS refractometer is the best by far.

Listen to disc1 -- he knows what's he's talking about.

And enjoy the new refractometer.

Mike

 

[JCulmo]

So far I am really loving the BRS refractometer. Quality and very precise