[lazy reef guy]

A Friend Of Mine Gave Me His Refractometer In The Case And It Has A Small Screw Driver To Calibrate It But Where Do You Start , My Older One And The One He Gave Me Have Different Readings , Mine Has 1.021 And The New One Is Reading 1.027 I Have Been Trying To Get Mine Up To 1.026 But Now I Fear That Mine Was Off Or His Is Off So Does Anyone Know How To Callibrate One

[thelastmucci]

honestly I've had the same question....my thoughts are bring it to a LFS and have them calibarte as they should know what their SW is testing.

[glampka]

You need to get some distilled water to calibrate it with (at least that's what I have to do). Water & refractometer should be at 77 degrees F. Put the distilled water on the plate & then adjust to get a reading of 1.0. Specific gravity is temperature dependent - the lower the temp, the higher the s.g. You could also go the manufacturer's website & get the directions there.

[pogodzib]

Some, in fact, most newer refractometers are ATC (automatically adjust from the temp.) so it doesn't need to be exactly 77 degrees, but many older models aren't. Pure RO/DI will be 1.000 when properly calibrated. You can also make your own calibration fluid or buy pre-made calibration fluid that is 33ppt for a couple bucks a bottle.

[thelastmucci]

thanks for making me look like a jerk guys hehe...j/k...glad to have the info.

[pogodzib]

Your welcome. BTW - I wouldn't bring it down to any old saltwater store. Most of them just use a hydrometer and say that it is accurate. They don't care that they may be using a hydrometer that may be off by 0.003-0.005 since they are only trying to keep the stuff alive long enough to sell it. If you do go that route, ask them if they have a refractometer that you can compare your to. Many times they will look at you like "what is a refractometer".

[thelastmucci]

yea my LFS uses a refractoemeter....the only reason I know is b/c I"ve seen it...silly me thought all LFS had them.