pprmntshrmps
New member
I bought a never used refractometer from someone. It is a bix refractometer with a scale of 0-30. Can I use this to test my salinity? If so how?
How to use a refractometer?
- Thread starter pprmntshrmps
- Start date
Google is your friend: http://www.grapestompers.com/articles/refractometer_use.asp
To get 1.025 SG, the line separating the dark and light color should be midway between the 1.020 and 1.030 scale on the left side.
I wouldn't trust it unless you've calibrated it with good RODI or distilled water and adjusted it to read zero.
To get 1.025 SG, the line separating the dark and light color should be midway between the 1.020 and 1.030 scale on the left side.
I wouldn't trust it unless you've calibrated it with good RODI or distilled water and adjusted it to read zero.
If its anything like ither one of my refractometers you put a drop of water on the flat end and look though the eye-peace towards the light and it will show your reading.
MotherFish
New member
Do NOT use FW (ro/di, distilled, etc.) to calibrate a refractometer.
I just wanted to get that out there first. I'll explain why in a moment.
pprmntshrmps, I may have some bad news for you...
It sounds like you've bought a brix refractometer for measuring the sugar content of alcohol/juices.
A refractometer for measuring salinity normally has two scales on the lens.
One scale reads ppt (0/00), which is 0 to 100 parts per thousand, and the other side of the scale reads specific gravity (d 20/20), which is 1.000 to 1.070
To find out what type of refractometer you have, hold it up to a light and look thru the eyepiece.
You have a proper salinity meter if what you see is this:
However, if what you see is this:
...then what you have is a sugar meter.
Now if you have the proper refractometer then you simply put 3 drops of your tank water on the glass lens, close the clear plastic cover, and look thru the eyepiece to read your salinity.
Most SW aquarists advise trying to keep a stable reading of 35ppt or 1.026sg on the average, which is a mid-level match for natural seawater.
Now getting back to the overly large, bold and red words at the top...
The reason you never use fresh water to calibrate a salinity meter is because the lens can have several different types of defects.
This is the reason there is a calibration screw in the first place.
If you calibrate a refractometer using FW then the only thing you can be 100% certain it will measure accurately is... yep, you guessed it,... fresh water.
It's not uncommon for a lens to read accurately at the precise point on the scale where it is calibrated to, yet get more and more out-of-whack the farther away the sample is from that point.
This is know as a slope defect.
Here is a visual example of what I am talking about from reefkeeping magazine:
The full article on everything you ever wanted to know about refractometers is here: http://reefkeeping.com/issues/2006-12/rhf/index.php
Happy reading!
Bottomline is, if you want to accurately measure 35ppt on your refractometer then you must calibrate it to 35ppt.
The best way (only way, in my book) is to use American Marine's Pinpoint salinity calibration fluid.
It has both the conductive property to calibrate digital meters as well as the refractive property to calibrate refractometers exactly to 35ppt.
You should be able to find a bottle of it at a LFS for about $5 and it will be enough to last you several lifetimes.
Happy reefing!
I just wanted to get that out there first. I'll explain why in a moment.
pprmntshrmps, I may have some bad news for you...
It sounds like you've bought a brix refractometer for measuring the sugar content of alcohol/juices.
A refractometer for measuring salinity normally has two scales on the lens.
One scale reads ppt (0/00), which is 0 to 100 parts per thousand, and the other side of the scale reads specific gravity (d 20/20), which is 1.000 to 1.070
To find out what type of refractometer you have, hold it up to a light and look thru the eyepiece.
You have a proper salinity meter if what you see is this:
However, if what you see is this:
...then what you have is a sugar meter.
Now if you have the proper refractometer then you simply put 3 drops of your tank water on the glass lens, close the clear plastic cover, and look thru the eyepiece to read your salinity.
Most SW aquarists advise trying to keep a stable reading of 35ppt or 1.026sg on the average, which is a mid-level match for natural seawater.
Now getting back to the overly large, bold and red words at the top...
The reason you never use fresh water to calibrate a salinity meter is because the lens can have several different types of defects.
This is the reason there is a calibration screw in the first place.
If you calibrate a refractometer using FW then the only thing you can be 100% certain it will measure accurately is... yep, you guessed it,... fresh water.
It's not uncommon for a lens to read accurately at the precise point on the scale where it is calibrated to, yet get more and more out-of-whack the farther away the sample is from that point.
This is know as a slope defect.
Here is a visual example of what I am talking about from reefkeeping magazine:
The full article on everything you ever wanted to know about refractometers is here: http://reefkeeping.com/issues/2006-12/rhf/index.php
Happy reading!
Bottomline is, if you want to accurately measure 35ppt on your refractometer then you must calibrate it to 35ppt.
The best way (only way, in my book) is to use American Marine's Pinpoint salinity calibration fluid.
It has both the conductive property to calibrate digital meters as well as the refractive property to calibrate refractometers exactly to 35ppt.
You should be able to find a bottle of it at a LFS for about $5 and it will be enough to last you several lifetimes.
Happy reefing!
Chris&Mel
New member
<a href=showthread.php?s=&postid=14126093#post14126093 target=_blank>Originally posted</a> by MotherFish
Do NOT use FW (ro/di, distilled, etc.) to calibrate a refractometer.
I just wanted to get that out there first. I'll explain why in a moment.
pprmntshrmps, I may have some bad news for you...
It sounds like you've bought a brix refractometer for measuring the sugar content of alcohol/juices.
A refractometer for measuring salinity normally has two scales on the lens.
One scale reads ppt (0/00), which is 0 to 100 parts per thousand, and the other side of the scale reads specific gravity (d 20/20), which is 1.000 to 1.070
To find out what type of refractometer you have, hold it up to a light and look thru the eyepiece.
You have a proper salinity meter if what you see is this:
However, if what you see is this:
...then what you have is a sugar meter.
Now if you have the proper refractometer then you simply put 3 drops of your tank water on the glass lens, close the clear plastic cover, and look thru the eyepiece to read your salinity.
Most SW aquarists advise trying to keep a stable reading of 35ppt or 1.026sg on the average, which is a mid-level match for natural seawater.
Now getting back to the overly large, bold and red words at the top...
The reason you never use fresh water to calibrate a salinity meter is because the lens can have several different types of defects.
This is the reason there is a calibration screw in the first place.
If you calibrate a refractometer using FW then the only thing you can be 100% certain it will measure accurately is... yep, you guessed it,... fresh water.
It's not uncommon for a lens to read accurately at the precise point on the scale where it is calibrated to, yet get more and more out-of-whack the farther away the sample is from that point.
This is know as a slope defect.
Here is a visual example of what I am talking about from reefkeeping magazine:
The full article on everything you ever wanted to know about refractometers is here: http://reefkeeping.com/issues/2006-12/rhf/index.php
Happy reading!
Bottomline is, if you want to accurately measure 35ppt on your refractometer then you must calibrate it to 35ppt.
The best way (only way, in my book) is to use American Marine's Pinpoint salinity calibration fluid.
It has both the conductive property to calibrate digital meters as well as the refractive property to calibrate refractometers exactly to 35ppt.
You should be able to find a bottle of it at a LFS for about $5 and it will be enough to last you several lifetimes.
Happy reefing!
So...what do you do if you live in the mountains....and there is only one "pet store" wich you would be lucky to be able to buy salt at?
pprmntshrmps
New member
Shortly after I got home and tried to test my salinity, and saw only the scale of 0-30, I did get on google and found ou that the brix that I have is not the one I needed. So is there no way to convert the reading on the brix to get salinity?
MotherFish
New member
A quick google reveals dozens of online places you can order it from.
I just found it for $4.99 at http://www.bluewatercorals.com/american-marine-pinpoint-salinity-calibration-fluid.html
and an even better price of $3.00 over at http://www.jcaquatics.com/id47.html
A refractometer is worse than useless if it isn't calibrated correctly.
I can't count the number of times a fellow reefer has been shocked to find out that what they thought was 1.026 on their ro/di calibrated meter actually turned out to be anywhere from 1.020 to 1.035 once it was adjusted using proper calibration fluid.
Considering the amount of money we've all got invested in our tanks, this is probably the smartest $5 you'll ever spend.
MotherFish
New member
Sorry, it is not made to measure salt.
Hopefully you can take it back for a refund and then you can buy the right one.
You can find the correct ones on ebay for about $30 with free shipping.
Good luck.
I agree that your best option is to take it back and get a proper refractometer for saltwater, however, if it is a refractometer, I don't see any reason why you can't use it for salt. Refraction of light through a liquid is the same thing regardless of whether you have sugars or salts in the solution. As long as the scale on the Brix includes the ranges of saltwater salinity that we care about (maybe 1.010 in the event you have to treat with hyposalinity sometime, to 1.0264), and you calibrate with the proper salinity standards, you should be able to make do with it.
You just need to have the proper standards to calibrate it against (like the Pinpoint solution mentioned above). Using a calibration standard like the Pinpoint solution, you should be able to tell where the 1.0264 SG equivalent is on the Brix.
If you're unable to get the Pinpoint solution, you might want to read the article below. It talks about making homemade salinity calibration standards.
http://reefkeeping.com/issues/2004-06/rhf/index.php
Having said all this, I personally don't think it's worth the trouble. If you have the option, just return it and get a proper refractometer.
You just need to have the proper standards to calibrate it against (like the Pinpoint solution mentioned above). Using a calibration standard like the Pinpoint solution, you should be able to tell where the 1.0264 SG equivalent is on the Brix.
If you're unable to get the Pinpoint solution, you might want to read the article below. It talks about making homemade salinity calibration standards.
http://reefkeeping.com/issues/2004-06/rhf/index.php
Having said all this, I personally don't think it's worth the trouble. If you have the option, just return it and get a proper refractometer.
pprmntshrmps
New member
Thanks everyone for the help. I'll keep looking for one that has a salenity scale.
