PDA

View Full Version : Using a Refractometer

dhebert24
11/21/2004, 05:47 PM
Hi all,
I just purchased a refractometer online, it came, but with no instructions! I have never used one of these before, so if anyone could help me out that would be great.. thanks very much
Adonis Mt
11/21/2004, 05:52 PM
Is it the one from Doc foster/smith? Check behind all the foam inserts..
thrlride
11/21/2004, 05:56 PM
First, put two drops of fresh water on the clear glass near the end and adjust the little screw to make it read 1.000.
Then clean of the fresh water and put the salt water on there and look through the scope. It should now read whatever you want you salinity to be.
Rick Newton
11/21/2004, 06:23 PM
I believe you should calibrate it with distilled water. At least thats what the instructions on mine said.
power boat jim
11/21/2004, 07:14 PM
You will also need to hold it under a fairly good light to get a reading on it, at least with mine you do.
AeroD79
12/09/2004, 06:39 PM
There's a small scratch on mines from Dr Fosters, im gonna get it exchanged since I dont feel right with it. Does yours have a small scratch? Distilled water give me a right reading so far.
power boat jim
12/10/2004, 09:28 PM
No, Mine did not arrive with a scratch. The glass surface is perfectly smooth.
xxticy007
12/16/2004, 08:17 PM
Glad I found this post. They like to hide those instructions behind every one of the foam inserts when you get the Dr Foster's Refractometer.. Unit looks nice, off to check it out..
xxticy007
12/16/2004, 08:18 PM
Can I also use RO/DI water to calibrate the refractometer? If I can does it matter if it is the RO or the DI water?
weimluv1
12/16/2004, 08:35 PM
well i calibrate mine using RO water, around 7 ppm. I get my salinity tested at the LFS and it's perfectly accurate, as far as i can tell.

but if you have DI water, why not just use it instead?
it only takes 3 drops.
ohioreef
12/16/2004, 09:33 PM
Originally posted by thrlride
First, put two drops of fresh water on the clear glass near the end and adjust the little screw to make it read 1.000.
Then clean of the fresh water and put the salt water on there and look through the scope. It should now read whatever you want you salinity to be.

Shouldn't the reading be 000 for freshwater?
Saltz Creep
12/16/2004, 10:43 PM
Pure water's SG is 1.000 (which is 1.000g/1cc).

If it were 000 it would be weightless.

RO, DI, and distilled water will read 1.000. Most tap water will too if the TDS isn't super high.
ohioreef
12/17/2004, 12:27 PM
My mistake, I thought you were talking about actual salinity not SG, where freshwater would be 0ppt.

Hope I didn't confuse anyone.