Calibrate Refractometer

F

Firedog1962

New member
Please remember to periodically calibrate your refractometer. I just checked the one I had been using for nearly two years and it was off by 4 points.
 
I try to check my refractometers on monthly basis or after dropping sometimes. Its rare to go more than couple point off. But good thing you checked.
 
calibrating fluid? I've never even heard of that until you said it. At the store, we always recommended using distilled water to calibrate, as it's truly pure water.
 
Same thing happened to me. I went about six months thinking it was calibrated from the manufacture. I've found it's off almost everytime I check it.
 
ryan_ said:
calibrating fluid? I've never even heard of that until you said it. At the store, we always recommended using distilled water to calibrate, as it's truly pure water.
Click to expand...

any measuring device should be calibrated in the range it is intended to be used. the accuracy from using RO to calibrate can vary on the refractometer. same goes for your digital thermometers (using ice water to 32 degrees - great around 32 degrees, not so accurate at 80).

Also, it is best to use a device near it's intended mid-point. for example, when I used to race sport bikes, I used a 60 PSI air pressure meter instead of a 30 for setting pressures at 24 and 26.5 PSI
 
Instructions that came with mine said to use distilled water. Distilled water actually has a specific gravity of 0.997 @ 77 degrees F.
I plan on checking mine with both the water & the calibration fluid which is @ 1.026.
 
I've been reading up on the solutions, how to make the different kinds, and the actual need to calibrate a refractometer for the last hour now. The type of refractometers used in this hobby only need to be calibrated with pure water. Now, if you are using one measuring brix (like the $1158.00 field model Reichert Full-Range Digital Refractometer), then yes, you need a special solution. But for your $50 model......no

I understand that there are many people out there who just need to have the next best thing offered, have money to wipe with, and love to have packages come in the mail. I also know that those of you who are reading this, will most likely fire off responses to argue the point of buying such items. So I write this to those who are new in the hobby.... DON'T WASTE YOUR MONEY!! The instructions for all refractomers that I have seen/sold have said to use pure water. ro/di is not pure water! spend the .80 at the grocery on a gallon of distilled.

Don't believe me? Go to any reef store. Ask them if they are using a calibration solution, if they say yes, I guarantee that they will then direct you to the shelf that they sell it from. If they say no (which 99% will), look at their DT, bet it looks pretty good.
 
if u took your refactometer apart, (i have)you would find a small ,clear piece of plastic with a graph printed on it. the screw alows the the graph to moved up or down. your tool will only be as accurate as your control solution. ideally, a lab grade solution of 35%. refractometer are very temperamental at best. they cannot measure anything. they are quite capable of comparing a water sample ,against a known water sample.
 
Dave VG said:
some good reading for ya

http://reefkeeping.com/issues/2006-12/rhf/index.php
Click to expand...

x2

It's especially important to calibrate our hobby-grade (read: cheap) refractometers with a solution that is close to the range we use them.

Calibrating in distilled or RO/DI water will not help with offset or slope miscalibrations (described in the article).

Make your own 35 ppt calibration solution and know that your salinity reading is accurate.
 
ryan_ said:
I've been reading up on the solutions, how to make the different kinds, and the actual need to calibrate a refractometer for the last hour now. The type of refractometers used in this hobby only need to be calibrated with pure water. Now, if you are using one measuring brix (like the $1158.00 field model Reichert Full-Range Digital Refractometer), then yes, you need a special solution. But for your $50 model......no

I understand that there are many people out there who just need to have the next best thing offered, have money to wipe with, and love to have packages come in the mail. I also know that those of you who are reading this, will most likely fire off responses to argue the point of buying such items. So I write this to those who are new in the hobby.... DON'T WASTE YOUR MONEY!! The instructions for all refractomers that I have seen/sold have said to use pure water. ro/di is not pure water! spend the .80 at the grocery on a gallon of distilled.

Don't believe me? Go to any reef store. Ask them if they are using a calibration solution, if they say yes, I guarantee that they will then direct you to the shelf that they sell it from. If they say no (which 99% will), look at their DT, bet it looks pretty good.
Click to expand...

totaly false, the refrectometer i bought came with the calibration solution, and it specifically said to use the solution to calibrate, as water will not accurately calibrate the refractometer.

fyi i got mine from a very reputable dealer.. Bulk reef supply. and i would rather be safe than sorry. and fyi refractometer calibration solution is cheap to begin with
 
Calibration Solution 110%. IME. I calibrate every day.

I use my refractometer about 20-30 times a day. It depends on what day of the week it is.:crazy1:
 
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more and more i use my floating glass hydrometer. other than keeping it clean and not breaking it , it's more reliable, and does not need to be calibrated.
 
Now that the holidays are over I finally got around to checking the calibration of my refractometer with the calibration fluid I got from BRS. Previously I had calibrated it with distilled water. I got a reading of 39 ppt on the 35 ppt standard solution.
 
ryan_ said:
I understand that there are many people out there who just need to have the next best thing offered, have money to wipe with, and love to have packages come in the mail. I also know that those of you who are reading this, will most likely fire off responses to argue the point of buying such items. So I write this to those who are new in the hobby.... DON'T WASTE YOUR MONEY!!
Click to expand...

It's not like anyone is suggesting that some high ticket purchase is a necessity. I bought calibration fluid for $5 over a year ago. I'm a frugal reefer and that was probably one of the least expensive purchases that I have made in the hobby.

To me, it's worth a few bucks to make sure that the specific gravity of my water is as close as possible to where I intend for it to be.
 
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