Red Sea Refractometer losing calibration

beachsidereefer · Feb 12, 2016

Hi Everyone,

recently I bought one and I've noticed it doesn't hold it's calibration for more then one to two weeks. I use 35 PPT calibration solution last week and today, when I used it, it's now reading 40 PPT so a delta of 5 PPT. Seems like a pretty big swing in calibration in such a short amount of time!

Thanks all for the replies!

http://www.redseafish.com/red-sea-salts/seawater-refractometer-salinity-test/

chefjpaul · Feb 16, 2016

do you use the same lighting every time?
I calibrate mine every use. mainly due to the fact I work different hours daily and the sun light is different.

clownfish chris · Feb 16, 2016

Temperature also plays a huge roll in calibration.

jent · Feb 16, 2016

A good refractometer should auto adjust for temperature.

Based off my research the RedSea refractometers are notoriously bad at maintaining calibration.

beachsidereefer · Feb 17, 2016

Yes, I use the same light source every time which is the LED lights over my tank.

wish I would have known that it has such a problem with holding calibration. My old one, which I think I spent 25 bucks on, lasted for years before I dropped it and held it's calibration for months at a time.

I thought by spending the extra money on a red sea model would be a nice step up in quality and craftsmanship but if I have to calibrate it every time I use it then the extra money i spent is a waste.

beachsidereefer · Feb 17, 2016

clownfish chris said:
Temperature also plays a huge roll in calibration.

according to Red Sea it compensates for temp. Also reading the web site it sure seems like it's the greatest refractometer ever made and I fell for it.

"includes Integrated Automatic Temperature Compensation (ATC) for accurate measurement at standard ambient temperature."

clownfish chris · Feb 17, 2016

I have the Red Sea as well. I used to make eyeglass lenses and am used to constant calibration. I calibrate it every time I use it. I didn't even know it had ATC. I guess I need to read the instructions more carefully ...LOL! I don't make adjustments very often though.

beachsidereefer · Feb 17, 2016

clownfish chris said:
I have the Red Sea as well. I used to make eyeglass lenses and am used to constant calibration. I calibrate it every time I use it. I didn't even know it had ATC. I guess I need to read the instructions more carefully ...LOL! I don't make adjustments very often though.

maybe my unit is defective. It's pretty consistent that if a week or two elapses between calibration it's off and I'm talking way off like 4- 5 PPT

jent · Feb 17, 2016

beachsidereefer said:
maybe my unit is defective. It's pretty consistent that if a week or two elapses between calibration it's off and I'm talking way off like 4- 5 PPT

Your unit is not defective. Search around, it's just a crummy refractometer if you ask me:

www.reef2reef.com/threads/red-sea-refractometer-constantly-needs-calibration.198277/

The last post has RedSea's response (which I have seen in several places):

It is required that the refractometer is calibrated before every use.

AFAIK, if you do calibrate it before every use it's great. But that is one refractometer you can't trust unless you _just_ calibrated it.

jetmaker · Feb 17, 2016

The red sea is supposed to be calibrated with distilled water.

beachsidereefer · Feb 17, 2016

jent said:
Your unit is not defective. Search around, it's just a crummy refractometer if you ask me:

www.reef2reef.com/threads/red-sea-refractometer-constantly-needs-calibration.198277/

The last post has RedSea's response (which I have seen in several places):

AFAIK, if you do calibrate it before every use it's great. But that is one refractometer you can't trust unless you _just_ calibrated it.

thanks for the reply. not only crummy but also expensive!

dacianb · Feb 19, 2016

I am using ro water and calibration liquid, just to be sure. RS recommend water, others not.
But if I calibrate with water, then the 35 solution is right on spot and vice versa.