Hydrometer vs Refractometer

[my2rotties]

I have the exact same hydrometer as you and bought the exact same refractomter as you yesterday as well. My salinity is .004 higher as well. Will be adding fresh water slowly now...

[midgetwaiter]

Double check your refractometer before you make changes. Pure water is NOT a good calibration standard for these things. Read this:

http://www.reefkeeping.com/issues/2004-06/rhf/index.php

[StirCrazy]

Originally Posted by midgetwaiter

Double check your refractometer before you make changes. Pure water is NOT a good calibration standard for these things. Read this:

http://www.reefkeeping.com/issues/2004-06/rhf/index.php

I read that and he said it is a good standard for initial calabration, but recomends that you check it once and a while against a sea water standard to make sure there were no manufacturing errors.

So basicly if you are using a good, refractometer the pure water is the way to calabrate it. It works for the labs and it will work for us.

If you have a questionable one then check it to make sure it is accurate at your SG

STEVE

[fishoholic]

.004 of a difference is normal between a hydrometer and a refractometer. That why refractometers are recommended. A friend of mine's hydrometer was out by .008, that is why hydrometers are not very reliable.

[Red Deer Reptiles]

just a quick note .those refractometers have to be calibrated did you get calibration fluid? you can do it with ro water. we use swc refractometers here. great results.dan

[ElGuappo]

correct me if im wrong as i dont have a refracto and i have used a friends to find out my hydro is out .0015 aprox. but are you not supposed to use distilled water to zero in a refracto?????/

[fishoholic]

Originally Posted by ElGuappo

correct me if im wrong as i dont have a refracto and i have used a friends to find out my hydro is out .0015 aprox. but are you not supposed to use distilled water to zero in a refracto?????/

Yes, distilled/RO/RODI, is what I've been told to use and RO is what I've used for calibration purposes.

[Red Deer Reptiles]

yes you can use ro water to calibrate remember ro water is at 0 so look in your refractometer if its not at zero adjust the screw to bring it to 0 been doing for 10 years.dan

[Red Deer Reptiles]

we suggest in the future have the store where you buy your refractometer calibrate it for you hope this helps.dan

[JDigital]

Your refracto should have come with calibration fluid, I got mine at Red Coral too, same one, and mine came with it.