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jjlove
05/14/2008, 06:16 PM
hey guys, my SeaTest specific gravity gage is reading 1.27 and my new refractometer is reading 1.3 Is the SeaTest that far off? or do i need to calibrate my refractometer? (which i have no clue how to do)

indydog1
05/14/2008, 06:26 PM
how did you calibrate the refractometer initially? is the sea test a swing arm type? i would recalibrate the refractometer then check the other one. refractometer is much more reliable.

Saltwater_Dog
05/14/2008, 06:26 PM
I use the pin point solution to calibrate my refrac...........

drparker
05/14/2008, 06:30 PM
Use this fluid $5 online to calibrate your refractometer. It will then be set to perfectly read 35ppt / 1.0264 salinity.

http://reefcentral.com/gallery/data/500/115488AM1437_1.jpg

Edit: +1, :D

cbrownfish
05/14/2008, 06:57 PM
Use RO/DI water and turn the screw until the reading is 0.000.

Tswifty
05/14/2008, 07:10 PM
<a href=showthread.php?s=&postid=12540746#post12540746 target=_blank>Originally posted</a> by cbrownfish
Use RO/DI water and turn the screw until the reading is 0.000.
that will get you in the ballpark... but get the solution to be certain.

kimoy
05/14/2008, 07:13 PM
<a href=showthread.php?s=&postid=12540523#post12540523 target=_blank>Originally posted</a> by drparker
Use this fluid $5 online to calibrate your refractometer. It will then be set to perfectly read 35ppt / 1.0264 salinity.

http://reefcentral.com/gallery/data/500/115488AM1437_1.jpg

Edit: +1, :D
where do you get this solution?

jjlove
05/14/2008, 07:20 PM
thanks lots, never did an initial calibration...i thought it would be okay from the factory

drparker
05/14/2008, 07:30 PM
The RO/DI as said will get you close. But most of the hobby grade refractometers have a slope error in the grid. So it can measure 0 fine but will be off the farther away from zero you get. The solution will set it to the range we use and thus will be very accurate.

I use to set mine with RO/DI and found that when I got the solution it was reading high by .003 so that I thought I was at 1.026 but was really at 1.023, even though it was calibrated to zero with RO/DI

I get it from Marine Depot, I also saw it in a better LFS for a few bucks more.

drparker
05/14/2008, 07:38 PM
Sorry wrong thread!