Refractometer

[Nalaundi]

Hey, I just purchased a refractometer and am wondering about the calibration solution. do I need to buy that too? if so how do I know which type. I just bought the refractometer off of ebay. Ive never used one of these before... hoping my half pint peabrained self can figure it out1 lol

 

[kewskills]

all you need is either RO water, or distilled water to calibrate it, don't waste your hard earned money on some rubbish calibration liquid its a rip off. lots of us use refractometers, if you have any problems when you get it just ask.

 

[Siamese Fighter05]

Yep just a bit of RO water will do it

Put you a couple of drops of water onto the plate and close down the cover. Look at the end and get your little screwdriver and while your looking into the end turn the screwdriver until the blue line hits the 0. Try and be as spot on as you can to increase the accuracy

 

[BigC]

Put you a couple of drops of water onto the plate and close down the cover. Look at the end and get your little screwdriver and while your looking into the end turn the screwdriver until the blue line hits the 0. Try and be as spot on as you can to increase the accuracy

Ditto
Regards
BigC

 

[Nalaundi]

fantabulous smiles.. you guys are my new best friends thanks

 

[andywg]

I am afraid that while the above is technically correct, in the real world it is not quite right.

The refractometers we can afford are cheap products and far from laboratory grade. Almost all will have a fair shift between reading 0 and 35ppt salinity. When calibrating refractometers you should always prepare a known salinity solution of 35ppt and calibrate to there.

A decent calibration liquid can be made yourself, but buying one which is sold as 35ppt is far from a rip off with the quality of refractometer we use.

 

[Musho3210]

they arent expensive at all, id agree with andy, or alternatively you could make your own (ive never saved the link... i know ski knows it).

What refractometer do you have? Cheap Chinese, quality German, or average American?

 

[SkiFletch]

(ive never saved the link... i know ski knows it).

Ski saved it for everybody Marine and Reef Chit Chat --> Realm of Knowledge Sticky --> Page 2. I agree with Andy, one has to make their own cal solution to check their refractometer or hydrometer for that matter.

 

[dilbert]

Here's a direct link to an article with some nice diagrams:

http/www.reefkeeping.com/issues/2006-12/rhf/index.php

In a nutshell, it says that many cheap refractometers are built for measuring brine and show about 2 units too much. So, when the water has SG 1.025, those refractometers measure 1.027.

So, people are saving salt with those refractometers if uncalibrated.

Calibration solutions from Pinpoint are actually quite cheap. GBP 1.49 a bottle from ebay. Vernier (ww.vernier.com) makes them, too.