refractometers

[reedman]

I was hoping someone (or several people) could enlighten me on what to look for in a refractometer. What justifies the higher prices vs. the budget versions. What are the goods and bads (i.e. temp compensation, light, calibration, etc.)

Thanks
-Reed

 

[wrightme43]

I got one from ebay, its the same one marine depot sells. ATC no light, Works great. Comes with adjustment screw driver, Just put 3 drops of 0 tds water on it, adjust to zero and then 3 drops of saltwater and check it. I have only had to adjust it once so far. Steve

 

[bc_slc]

I agree, the cheap ones from ebay are just fine. RO water is the calibration and they should all come with a screw. The major diff between the cheaper and the more expensive ones is some of the parts are metal vs plastic, but the actual refractor works the same.

Mat

 

[Wolfesbane]

To piggyback on Reed's question... alot of the refractometers on eBay say that they're used for antifreeze or battery liquids, wine, and stuff like that. Is there any difference between those items and the ones we use for our tanks or are they just marketing the same product to a different audience?

~ Steve

 

[Scooterman]

http://www.customaquatic.com/customaquatic/searchhomekeyresult5.asp

I have a tropic Marian, these are the real thing.

 

[esmith]

Reed, I got mine from Premium Aquatics and it works great. It was the least expensive one I could find, that said it was for salt water use, at the time I bought it...I believe big T ordered the same one as well.

http://www.premiumaquatics.com/Merc...duct_Code=REFRACT-PA&Category_Code=Hydrometer

-Eliyah

 

[DonW]

Thants the one I have. Works fine. Never had to adjust.

Don

 

[Boomer]

Is there any difference between those items and the ones we use for our tanks

Yes, for some of them. You need one for water or for liquids heaver than water. The range in SG of about 1.000 - 1.040 or a little more or %, 0 - 4.0 % or a little more, or ppt, 0 - 40 ppt or a little more

This one, that Eliyah posted , is by far the most common in the hobby. It is made in China and it is fine for us.
Premium Blue Refractometer - RHS-10ATC
The one Scoot posted is also fine
http://www.customaquatic.com/customaquatic/searchorderitems.asp?itemid=DI-MKMR100-ATC



Works fine. Never had to adjust.


Yes you do A refract is off " - 15" units, right out of the box.

99.99 % of all refractrs, we would use in the hobby, are calibrated to NaCl Salinity. Salinity does not mean seawater salinity, it could be KCl, NaCl Salinity etc.. It is the salinity of any "salt". Seawater Salinity is not the same as NaCl Salinity or KCl Salinity, each has its own RI (Refractive Index). In other words, a 35 ppt NaCl RI is not the same as a 35 ppt RI for KCl or Seawater. In order to calibrate a refract to NSW you would want a sample that had the same RI as seawater. So, that would be a sample of seawater that is know to be 35 ppt or to mathematically calculate a salinity using another salt that would = NSW. Such is the case with the 3.65 % NaCl, which = NSW @ 3.5 % Salinity. So, what is a" - 15 " unit ? It means the refract is reading an SG of .0015 to low, .15 % to low or 1.5 ppt to low. So, for the refract for SG, you would want it to read ..1.0265 SG + .0015 SG = 1.028SG = NSW. SG............FOR %, 3.5 % + .15 % = 3.65 % NSW %......... FOR ppt, 35ppt + 1.5ppt = 36.5ppt = NSW ppt

 

[Woodstock]

I've heard of people using distilled water but you state that is not a true calibration...I once tried to make the calibration fluid (35ppt salt mixture) using a recipe online (sorry can't find the link now) and it was a flop. Can a ready-to-go calibration mixture be purchased online??

 

[Elmo18]

Reed, I got mine from Premium Aquatics and it works great. It was the least expensive one I could find, that said it was for salt water use, at the time I bought it...I believe big T ordered the same one as well.

http://www.premiumaquatics.com/Merc...duct_Code=REFRACT-PA&Category_Code=Hydrometer

-Eliyah

That is the same exact one I use. Nice and blue...easy to use...

- Elmo

 

[DonW]

Boommer,

I think your the one that told me this in the past. So I tested rodi set at zero. Then made SW to 35ppt the back adjust down to 33.5. Then rechecked with ro and its around 1/8" below the 0 line. Never had to adjust again alway reads 1/8 below 0 with rodi.

Is this correct??

Don

 

[Ed Hahn]

Reed,
I bought a Sybon premium refractomer with club money on sale at one time for 59 dollars from Premium Aquatics. Sybon has been around for a while. I bought a refractomer from Fosters and Smith for 42 dollars. The only difference between the two that I have noticed when comparing them was the weight. The heavier one from premium aquatics is suppose to be a good unit. My cheaper model has had no problems with it yet. They both have been accurate for me as far as I can tell. They both are temperature compensating. You want to make sure your refractomer is room temperature or it could affect your readings.
hope this helps,
Ed

 

[NaH2O]

Here is a link to the Reef Aquarium Salinity: Homemade Calibration Standards

I thought there was a calibration fluid you can purchase. For some reason I thought Salifert made one because I remember seeing a little bottle at their booth when talking with Habib in Boston.

 

[bc_slc]

I have the same blue one as well. I paid less than that however. If you do a search on "froogle" and enter "RHS-10ATC" you can find it cheaper. Just on a quick search (by no means exhaustive), I found it for $42.00

 

[Boomer]

Woody

Can a ready-to-go calibration mixture be purchased online??

Yes there are Someone who sells IAPSO Standard Seawater, like
http://www.seawatersolutions.com/

You will need lots of money $437.46




Don

Then made SW to 35ppt the back adjust down to 33.5

Yes that is just fine IMHO. That 35ppt SW mix would be equal to 35 ppt NaCl and the real NSW salinity would = that 33.5 ppt (35 - 1.5 = 33.5). Turn the calibration screw till it reads this on the refract (33.5). No if you added more salt till it got to 35 ppt, this will be the same as or close enough to NSW 35 ppt. Try to do it with water and refract @ 77 F


Nikki

For some reason I thought Salifert made one because I remember seeing a little bottle at their booth when talking with Habib in Boston.

Yes, that is correct, and he was giving them away to see what reefers thought of them.

 

[LCATTIN]

I like the Sybon from Premium Aquatics as it is heaver duty. I am a bit of a klutz at times and the HD model has more metal in it and is less apt to get messed up if accidently dropped. Worth the extra $15.00.

 

[NaH2O]

LCATTIN - Welcome to Reef Frontiers!!!

Boomer had made mention earlier in the thread about correcting refractometers by -15 units

Works fine. Never had to adjust.


Yes you do A refract is off " - 15" units, right out of the box.

99.99 % of all refractrs, we would use in the hobby, are calibrated to NaCl Salinity. Salinity does not mean seawater salinity, it could be KCl, NaCl Salinity etc.. It is the salinity of any "salt". Seawater Salinity is not the same as NaCl Salinity or KCl Salinity, each has its own RI (Refractive Index). In other words, a 35 ppt NaCl RI is not the same as a 35 ppt RI for KCl or Seawater. In order to calibrate a refract to NSW you would want a sample that had the same RI as seawater. So, that would be a sample of seawater that is know to be 35 ppt or to mathematically calculate a salinity using another salt that would = NSW. Such is the case with the 3.65 % NaCl, which = NSW @ 3.5 % Salinity. So, what is a" - 15 " unit ? It means the refract is reading an SG of .0015 to low, .15 % to low or 1.5 ppt to low. So, for the refract for SG, you would want it to read ..1.0265 SG + .0015 SG = 1.028SG = NSW. SG............FOR %, 3.5 % + .15 % = 3.65 % NSW %......... FOR ppt, 35ppt + 1.5ppt = 36.5ppt = NSW ppt

This has since been corrected for those that use the blue Xiamen Ming Xin RHS-10ATC, as they don't have to be adjusted. For more info see this thread: Randy's Refractometer Calibration Summary

 

[Boomer]

Thanks Nikki, I was just going to point out Randy's tests It is more than likley it is our luck that they are in error from the factory. We are hoping Randy does a test on a more std hi-quality lab grade unit to see what they read. We know that based on how refracts work and what they are calibrated to they should follow the "15" rule This is why some compaines make refracts specifically calibrated to NSW but they cost an arm and a leg for one.