how to read your refractometer

[SnowManSnow]

do i go by SG or PPT? Do i shoot for 1.025 sg at around 76F?

why am i confused about this? maybe its just too late!

b

 

[ChrisRD]

I shoot for 35 PPT. If you have a newer unit that has ATC it shouldn't matter what temp the sample is - it should correct for this.
For reference, a commonly accepted average value for NSW is 35 PPT and SG=1.0264 @ 25 degrees C (77 degrees F).

If the refractometer is new, personally I would zero it with freshwater and then use a calibration solution made from tablesalt to make sure it's hitting S=35 accurately.

Article by Randy discussing the homemade calibration solution:
http://reefkeeping.com/issues/2004-06/rhf/index.php

HTH

 

[bleedingthought]

How does the reading change (or what should I be aiming for) when the temperature is different?

Is there an equation? Trying to figure out what salinity the refractometer should read if the temp is around 81 degrees and there's no ATC.

 

[SnowManSnow]

yea i do have one with ATC.... wow ive been going with 29 ppt! no everything is LIVING .. but not really thriving.. no wonder.

haha just dont tell anyone~

b

 

[helipilot]

I use this recommended method of calibrating and reading my refractometer. I use a known salinity solution for calibration. My refractometers are then right on. http://www.reefkeeping.com/issues/2004-06/rhf/index.php

 

[SnowManSnow]

im SLOWLY raising my PPT today and tomorrow in my 65 cube

b

 

[bleedingthought]

What about the temperature though? :?

 

[SnowManSnow]

temp is remaining constant

If you have a meter with ATC (automatic temp calabration) you will get an accurate reading of your salinity reguardless of the temp.

b

 

[ChrisRD]

How does the reading change (or what should I be aiming for) when the temperature is different?

Is there an equation? Trying to figure out what salinity the refractometer should read if the temp is around 81 degrees and there's no ATC.

It's definitely possible to calculate it if you know the temp the unit was calibrated for and know the temp of the sample, but personally, I don't think you need to go through all that. Considering we run our tanks at relatively consistent temps, I would just calibrate the unit with the solution mentioned in Randy's article linked above. Just have the calibration solution at around the average temp you're running the tank at. That should be accurate enough for our purposes IMO.

 

[bleedingthought]

How does the reading change (or what should I be aiming for) when the temperature is different?

Is there an equation? Trying to figure out what salinity the refractometer should read if the temp is around 81 degrees and there's no ATC.

It's definitely possible to calculate it if you know the temp the unit was calibrated for and know the temp of the sample, but personally, I don't think you need to go through all that. Considering we run our tanks at relatively consistent temps, I would just calibrate the unit with the solution mentioned in Randy's article linked above. Just have the calibration solution at around the average temp you're running the tank at. That should be accurate enough for our purposes IMO.

Thanks Chris!