how to calibrate a refractometer

Discussion in 'Test Kits, Controllers, Reactors and Dosers' started by shaunn, 23 Jan 2012.

  1. shaunn

    shaunn

    Joined:
    26 Sep 2011
    Posts:
    2,179
    Likes Received:
    36
    Location:
    JHB
    hi guys

    I finaly got me a refractometer but how do calibrate it

    this what i have done
    got some distilled water and ajusted the screw to were it says 0 is this the correct why of calibrateing it ? could sombody with more experance maybe calibrate it for me ?
     
  2. AdS Guest




    to hide all adverts.
  3. belindamotion

    belindamotion Google Master

    Joined:
    24 Jan 2011
    Posts:
    4,803
    Likes Received:
    134
    Location:
    Pinetown,South Africa(KZN)
    Sounds about right...

    Refractometer Calibration - Marine Aquariums of South Africa
    Calibrating Refractometer - Marine Aquariums of South Africa
    Refractometer - Marine Aquariums of South Africa
     
  4. Nemos Janitor

    Nemos Janitor

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    No no no no.

    Let me explain properly. Give me a few moments to type this up so all understand.
     
  5. belindamotion

    belindamotion Google Master

    Joined:
    24 Jan 2011
    Posts:
    4,803
    Likes Received:
    134
    Location:
    Pinetown,South Africa(KZN)
    Last edited by a moderator: 26 Nov 2015
  6. rakabos

    rakabos

    Joined:
    12 Jul 2010
    Posts:
    5,006
    Likes Received:
    91
    Location:
    Wilgeheuwel, JHB
    You need to calibrate it using the same temperature to the water you want to test. Use tap water to zero it at say 26C. Then test the tank or mixed water given that it is also at 26C
     
    Last edited: 23 Jan 2012
  7. Nemos Janitor

    Nemos Janitor

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    Dbl post
     
    Last edited: 23 Jan 2012
  8. Nemos Janitor

    Nemos Janitor

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    OK we are talking about hand held refractometers. Their are two basic types. Ones with ATC (Automatic Temperature Compensation) and ones without. There are also different scale ranges. Some for sugar some for brine some for urine etc. Most of the refractometers sold in the hobby are Brine refractometers. There is one refractometer available that is specifically calibrated for salt water.
    Refractometers are measuring the refraction of light. Converted this is the measures the SG(specific gravity) of the water we are testing. Because SG is a weight to volume measurement temperature plays a big part in the calibration and measurement. In the article by RHF he recommends that refractometers are best calibrated with a substance that has a SG close to that of the sea water to be tested. I agree but it is very difficult to find a reference substance that is calibrated to 20c which most refractometers are calibrated to. Most calibration fluids for SG are referenced at 25c. So we will stick to RO water.

    Calibrating a ATC refractometer.

    If one looks through the eye piece at the scale there should be a reference temperature indicated on the scale. This is sometimes indicated as 20/20 or 20c. This is the temperature that the instrument must be calibrated at.

    So the first step is to make sure the instrument is at 20c
    When the instrument is at 20c add a drop or two of Ro/DI water to the prism. Do not bother about the temperature of the RO/DI water as the small amount of water will quickly equalise to 20c. Now make sure to hold the refractometer on the rubber grip when using as body temperature will increase the temperature of the instrument if held on the body of the instrument. By adjusting the calibration screw calibrate the refractometer to read zero or it is on the 0 calibration point. Your refractometer is now ready for use.
    You can now go and test your salt water at almost any temperature and the ATS will compensate and give you a SG reading AT 20c.

    Bare in mind that if you want to keep your SG at 1.025 at 25c which is a salinity of 35ppt then one should aim for a reading on your refractometer of 1.0264. This is because the refractometer is calibrated at 20c.

    Non ATC Refractometers.

    Same as above applies except that instrument needs to be at the same temperature as the calibrated temperature. This also means that the SG reading will relate the that temperature.

    If there are any Q or uncertainties please ask.

    Refractometers and Salinity Measurement by Randy Holmes-Farley - Reefkeeping.com
     
    Last edited: 23 Jan 2012
  9. shaunn

    shaunn Thread Starter

    Joined:
    26 Sep 2011
    Posts:
    2,179
    Likes Received:
    36
    Location:
    JHB
    how do i make sure the instrument is @ 20c and btw it's a H2 Ocean one and can i use distilled water ?
     
  10. Nemos Janitor

    Nemos Janitor

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    Proper distilled water is OK.

    In SA it is a little more difficult than in EU countries where the room temp is normally around 20c but I just calibrate every now and again after leaving it in the bedroom with the air-con on and set to 20c.
     
    Last edited: 23 Jan 2012
  11. mariusmeyer

    mariusmeyer

    Joined:
    7 Jul 2009
    Posts:
    3,055
    Likes Received:
    210
    Location:
    Jukskei Park, JHB

    I can just see the look on my wifes face when I tell her we need an aircon so that I can calibrate my refractometer :lol:
     
  12. Spook

    Spook

    Joined:
    14 May 2013
    Posts:
    4
    Likes Received:
    0
    Location:
    Standerton
    calibrating Vertex refractometer

    Hi, every1 ~ I am new to this forum but not completely new to marine aquariums. Since school days I hav kept some marine fish (fish only). I did all these years kept gouramis which I am addicted to. Recently I decidede to set up a "softies" tank (soft corals/anemones). I do hav a zoa, cushion stars, mini carpet anemones, pinktip anemone, hermit crabs, ext ~ all doing very well. Here is my bigggest problem: I decided to invest in a proper refractrometer a couple of weeks ago ~ a Vertex ~ but I am havn a big problem calibrating it (I grow rare plants/hydroponics), so I use instruments (ph, tds, ext) on a daily basis. I just can't calibrate my new "superior" refractometer !!!. Had a look on the internet and found diffirent Vertex refractometers (the "real" one and mine ~ that looks very much like Premium Aquatics' one except the sticker on the case says "Vertex). Extech/Nashua send me a pic of their Vertex refractometer and it does not look like mine. In short ~ I am a bit confused *_* ~ do I have a real Vertex (or not) and why can't I properly calibrate it ???. Seems like I don't have a real Vertex that is not ATC. Does any1 use a VERTEX refratometer with a light grey case, black inside, with a plastic pipette, small yellow screwdriver, brown cloth and a user manual stating all the diffirent models. The Vertex sticker on the plastic case is silver with black/red lettering "VERTEX. portable refractometer" ~ which can easily peel off saying "hand held refractometer" on the case. Does any1 own such a refractometer too and can you tell me what RHS series/model it is and if it is ATC plus how to calibrate it ???? (I do have DI and 35 ppt standard solutions). Trust me I have tried everything to calibrate it for longterm use (must recalibrate before every use). Much appreciate any info/help ~
     
    Last edited: 3 Jul 2013
  13. carlosdeandrade

    carlosdeandrade

    Joined:
    24 Dec 2010
    Posts:
    8,230
    Likes Received:
    228
    Location:
    North Riding, Jozi
  14. Spook

    Spook

    Joined:
    14 May 2013
    Posts:
    4
    Likes Received:
    0
    Location:
    Standerton
    Havn difficulty uploading photos (no suprise ~ I am on a farm with a veeery bad internet connection). Plz be patient ~ I will try aqain ~
     
  15. Spook

    Spook

    Joined:
    14 May 2013
    Posts:
    4
    Likes Received:
    0
    Location:
    Standerton
    Seems like it is going to be difficult for me to uploadi photos ~ I will try again over the weekend. Thank you for your patience ~
     
  16. ShLiMi333

    ShLiMi333

    Joined:
    26 Feb 2016
    Posts:
    379
    Likes Received:
    54
    Location:
    Welkom
    I have the redsea refractometer and is calibrated with distilled water heated to 25deg. is this the proper way to calibrate it?
     
Recent Posts

Loading...
Similar Threads - calibrate refractometer Forum Date
Calibrate your testing equipment. General Discussions and Advice 14 Aug 2013
Refractometer broken General Discussions and Advice 26 Sep 2016
[wtd] refractometer and ro unit Wanted 2 Sep 2016
ATC Refractometers @10% more off our already LOW prices Sponsor Specials 18 Aug 2016
hand held refractometer question Test Kits, Controllers, Reactors and Dosers 17 Aug 2016
[wtd] RO unit and refractometer and ATO Wanted 3 Aug 2016
[wtd] Looking for refractometer Pretoria East Wanted 1 Aug 2016