SG Swing arm units VS. Refractometers

Scuba Dan · 06-15-2006, 02:39 PM

Received my Refractometer today. Checked reading with distilled water and read 0....Good.

Put a few drops of the tank water and it read 1.24 so I got out 2 of my SG swing arm units. The Coralife read between 1.20-1.21 the Sea Test Unit read 1.21 and like I stated, the refractometer read 1.24. I know the Refractometer is suppose to be better, but odd that the SG swing arms were that close together, while the Refractometer was .03-.04 higher. Hmmmmm... Should I adjust SG to refractormeter readings? I purchased the unit from Dr's Foster & Smith. Pic of unit below.
Thanks.....

forenpa1 · 06-15-2006, 02:58 PM

The refractometer is correct especially if it automatically corrects for temperature- remember the swing arms are calibrated for a specific temperature

Scuba Dan · 06-15-2006, 03:01 PM

I dont think mine automatically corrects for temperature. When using a Refractometer, you just make sure that the water and unit is at room temp. correct?

Caoineag · 06-15-2006, 05:20 PM

Actually, it does calibrate for temperature, I know because I have the same one. Your instructions will let you know how to calibrate and all you have to do after that is add water and read.

Twitterbait · 06-16-2006, 11:47 AM

I have the same one too. make sure to calibrate before testing each time. they work great

ChrisPrusha · 06-16-2006, 10:13 PM

My swing arm hydrometer began to read low after a while. The reason I know that is I purchased the same refractometer that you have, and my SG read about 1.030. I tested it against a new hydrometer and they were about the same...1.030.

The 6 month hydrometer read 1.026.

I don't use hydrometers much anymore. To be fair, though...I prolly didn't clean my hydormeter as thoroughly as I should have.

motorslave · 06-17-2006, 08:52 AM

I have the same refracto and they are great and as said it does correct for temp. Just calibrate each time!

Robert