Refractometer Calibration

[bobf]

After much frustration with a conventional hydrometer I've ordered a refractometer to keep an eye on SG.

Like you do, I've been reading the instructions (online) on how to use it while I wait for delivery - probably after xmas now.

The instructions mention that distilled water should be used to calibrate this - to set the zero, before first use. I just wondered, would RO water do the job as well? (Mine comes out at 0 PPM since I added a DI unit).

 

[Mr.September15]

If your going to use R/O water might as well calaborate it with R/O water. This is just an assumption, since I never had the money to get a refractometer ...I'll google it to see what I find.

Edit: I found the same thing...They all say to calibrating it with DI water. Skifletch has a refractometer tho . Now we just need to wait until he comes back from work.

 

[SkiFletch]

Lol, yeah, RO water should be fine. I use RO water to cal mine then check it against a 35ppt solution.

 

[bobf]

Lol, yeah, RO water should be fine. I use RO water to cal mine then check it against a 35ppt solution.

Thanks chaps - i think we all ended up reading the same article. Found this after my post.

Reefkeeping.com

Not that expensive actually Mr S - the one I've gone for is $21.90 plust carriage (cheaper for me in the UK paying in USD than buying sterling listed item because of the strong UKP)

theifbay

How did you get hold of a 35ppt test sample Ski - just SW tested against another refractometer?

 

[tmreynolds]

Been after one of these, since I don't trust my £2.95 hydrometer.

Just picked the same one up from eBay for ~$30, given the Exchange rate, as you mention, its a good deal

 

[SkiFletch]

Bobf, there's a link towards the bottom of that article you posted to Randy's previous article where he talks about making your own cal standard

DIY Calibration Standards

 

[bobf]

Bobf, there's a link towards the bottom of that article you posted to Randy's previous article where he talks about making your own cal standard

DIY Calibration Standards

Great - thanks Ski. I never looked that far down. Will give it a go whenever the refractor turns up.

 

[ostrow]

Yes, callibrating to zero only will not help as these things are not made for seawater (generally). I had a guy in my Univ's chemistry lab mix a solution, I believe to 36.5ppt with nacl. That corresponds to 35ppt seawater. Works like a charm.

Or you can buy for under $10 the callibration fluid in a bottle. Either way.