refractometer

[khmer86]

hey guys. is there a special refractometer to purchase or is it just all about the same? im trying to get one but i saw a few refractometers and im not sure which is better mode....which did u guys purchase or would recommend?

0-10% ATC New Salinity Refractometer with Adjustable Focus and Built-in Calibration Knob (RHSN-10ATC)

Features:

NO NEED for a CALIBRATION SCREWDRIVER to calibrate
Focus is adjustable and can be controlled manually
Equipped with built-in calibration knob
Comes with 3 years warranty and a non-roll stand
With much lighter weight and longer
Equipped with dual-scale measurement which provides direct reading
High quality and accurate testing results are guaranteed
Equipped with Built-in ATC compensation Range (Automatic Temperature Compensation) from 10° C-30° or 50° to 86°F to correct temperature discrepancies during use
Approved by strict quality and safety standards
Durable, Heavy-duty and lightweight with its aluminum construction
Made with the highest and finest quality of aluminum & rubber
Cushioned with soft & comfortable non-slip rubber
Comprehensive operations manual, complete with protective carrying case, and pipettes are provided for user's convenience and comfortability

Specifications:

Measuring Range: 0-100 ppt of NaCl and 1.000 to 1.070 Specific Gravity (0-10%)
Divisions: 1 ppt / 0.001 Specific Gravity
Accuracy: ±1 ppt / 0.001 Specific Gravity (±0.10%)
Length : 200mm
Weight: 185g
Heavy duty (Durable Aluminum)

[snorvich]

I don't have a specific brand to recommend but the one you are describing sounds fine to me. I personally have a battery powered light inside but my eyes are not as good as most of you. Be sure and get pinpoint calibration fluid (1.0264)

[khmer86]

wats pinpoint calibration fluid?

[celano]

^^^Also what brand do you have with a light in it? My eyes arn't that good either and I always have hard time reading mine.

[Joe]

<a href=showthread.php?s=&postid=14611253#post14611253 target=_blank>Originally posted</a> by khmer86
wats pinpoint calibration fluid?

http://www.marinedepot.com/ps_searchItem.aspx?IdCategory=&SearchText=salinity+calibration+fluid&parsed=1

Joe

[ccolt1]

I have one that is a RHS-10ATC and it says to use ro water to calibrate to zero.I bought it used and have not used it yet but will be.Does that sound right about the ro? Thanks... It's made by National Industrial Supply.

[Joe]

Do NOT calibrate with RO or distilled water. Use the lab certified 35 ppt calibration fluid.

Joe

[schneijt]

You "can" calibrate it to zero with RO/DI water. However, it's best to calibrate it using the 35ppt fluid that they sell specifically for calibrating your refractometer. The reason is because there could be a small amount of "error" in your refractometer. So, the further you go from your calibration point, the greater possible errors in the reading could become. By using a calibration solution that's at the same salinity as seawater, you greatly reduce the chance of having any stray readings when you test the salinity of your artificial saltwater.

-Joe

[khmer86]

just bought a refractometer from ebay. hope it comes soon and is in new condition for half the price at lfs :)

[hairyman1]

Yeah I read that article that recommended the calibration fluid and I was suckered into trying it out. I found no difference between the
4 oz. pinpoint solution and 1 gallon of walmart distilled water. My manufacturer recommends distilled water to calibrate and at .68 cents a gallon vs $4.99 for the pinpoint solution I'll stick with the distilled. Now if your refractometer was not made for seawater than calibrating with the pinpoint solution may make sense. RO/DI should work too as long as your TDS meter reads 0. The main thing is to use the device correctly according to the instructions and then verify the results with other devices if you have any. I have an original aquarium systems swing arm hydrometer and a hand made tropic marin hydrometer along with the RHS-10ATC cheapo $39.00 refractometer. The main thing for my unit is to calibrate when the room air temp. is at 68 degrees and make sure the calibration sample is spread out over the entire prism. At 75 degrees tank temp my S.G. is 1.026 with the refractometer and the tropic marin. My old swing arm reads 1.024. With slight differences like that I can't kill anything regardless of what instrument I use. Now what I would like to see is some hot shot tell us how to calibrate a swing arm. LOL.