How often calibrate refractometer?

[delta]

I calibrate mine if i drop it or once a month or so. I used a calibration solution pretty cheap.

I believe Randy did a study on using RODI and got conflicting results. The way I look at it is
better safe than sorry. So I use a calibration solution

 

[JohnK]

Yea, I've heard all sorts of conflicting advice about calibration.

I have heard that RO, tap, and even distilled water may not be ideal. I guess that's why calibration solution has been on my "to get" list for the past two or three yrs .

 

[Blueflu1]

I have had my refractometer for 4 years. I calibrated it for the first time 4 months ago and it was only 1 tenths off. I use distilled water.

 

[toolfanatic]

No RO. No distilled. No tap.

So what's calibration fluid made of?

Aquafina?

 

[snowmaker]

I'm not sure about refractometers, but usually, when you calibrate anything you should cal. at or near the value you usually measure. For instance, cal. solution should be somewhere around 1.025, not 1.000, or 1.1000.
Test instruments are typically designed with an operating range in mind, and should be calibrated within this range.
Get a cal. solution

 

[stevenp]

IMO, calibrating with tap or RO is still 100 times better than not calibrating at all.

 

[pillowfish]

I calibrate mine just about every time I use(or at least check it to make sure it is still exactly where I want it). I use RO. I'm not saying how often I actually use it though

 

[Cheetos]

For those who want to know why to use calibration solution instead of RO water.....
http://www.reefkeeping.com/issues/2006-12/rhf/index.php#11

 

[snowmaker]

Wow...

All you'd ever need to know and then some.

 

[toolfanatic]

Ok, the discussion prompted me to check it. Two point calibration at 0 ppt and 35 ppt. No need for adjustment.
I think if your going to check you should use a standard otherwise you won't know the true setting. I think a 0 ppt fluid is distilled H2o. I'm going to compare readings for cal. fluid, RODI and distilled water to see if there's a difference. I'll also try tap water even though everyone's tap water is different.
Using a 2 point calibration you can be very sure it's correct.

I have a Sybon refractometer with temp compensation just for reference.

 

[Jim Tansey]

"Using a 2 point calibration you can be very sure it's correct."

Not if your calibrations standards are in question.

Jim

 

[dcforester1]

I purchased a refractometer about a month ago, and I have to calibrate it everytime I use it. It was bought at Dr F&S, the $50 one. My friend has one, and it is never off. Mine is off 1-5 points, way to much IMO. Has anyone had this happen, or am I doing something wrong. I am thinking of returning it, but I know alot of people have the same one with no trouble. I use the solution to calibrate, I think its best to use, because like snowmaker said you are suppose to calibrate at the point you want your readings at. RO is to far off.This is getting annoying.
Thanks Derek

 

[ljr]

about every six months with calibration fluid.

 

[agentfive]

I use RO and calibrate it on the day of my filter change monthly.