SG and PPT in refractometer

[SteveCGY]

Originally Posted by gregzz4

Raied, why not run an experiment ?
Take out a cup of tank water, cover it and let it sit until room temp
Then compare it to your tank water

Good idea I have just done this, also added a cup to the fridge for comparison

[SteveCGY]

So
1oz fresh out of tank water measured 1.025
1oz tank water left out covered for 1 hour measured 1.025
1oz tank water left in fridge covered for 1 hour measured 1.025

After this I don't think tempature is a factor.

[hillegom]

Is that why mine says automatic temperature compensated?

[gregzz4]

Originally Posted by hillegom

Is that why mine says automatic temperature compensated?

Lol. I'd say the experiment is a bust if his is also an ATC unit

[SteveCGY]

Originally Posted by gregzz4

Lol. I'd say the experiment is a bust if his is also an ATC unit

Lol doh, mine is ATC 10-30C

[MitchM]

It won't matter what temperature your water is at.
1 drop of water will become the temperature of the instrument in a few seconds anyways.
Put the ATC refractometer in the fridge, or out in the sun, and that 's what it will compensate temperature for.

[mrhasan]

Sorry for getting back to this thread after a long time.

Anyway, my question was that in various forums, I always see people telling to measure PPT instead of SG and that's where I am scratching my head. Like does SG scale move up or down and ppt remains fixed? Because as far as I can see, the scale is fixed while for ATC, the metal strip expands or contracts for temperature compensation to show 1.026 - 35ppt ratio. Is measuring SG and PPT the same in a ATC refrac then?