Caution for anyone using a refractometer

[jasond]

I use RO as well....I might have to give this a shot...

[fencer]

Don't forget that density is dependent on temperature of your sample. Unless you have a correction factor your salt mix will be off.

[Doo]

ok - so how do I fix that?

My temp is at 79.0

[Reefer Rob]

Originally Posted by fencer

Don't forget that density is dependent on temperature of your sample. Unless you have a correction factor your salt mix will be off.

The 2 or so drops that you put on your refractometer will go to room temperature pretty quick Has anyone noticed a change in reading as the sample cools on the refractometer? I think the specific gravity may change with temperature, but not the refractive index.

[Reefer Rob]

The problem is that a lot of the refractometers that find their way into the aquarium industry are for measuring brine, as in for the pickling industry. Our salt water has a lot of other major elements that also effect the refractive index of the water.

According to Pinpoint, their calibration fluid also works well to calibrate our refractometers.

Here's the original thread that spawned Randy's article.

[Doo]

so - aside from the PINPOINT product - are there other products that can be picked up locally??

[Reefer Rob]

Originally Posted by Doo

so - aside from the PINPOINT product - are there other products that can be picked up locally??

As far as I know Pinpoint is the only one. Thats what everyone who posts on RC is using. Alternatively you could find a buddy that uses a well calibrated salinity monitor on their tank, and use their tank water to check your refractometer.