Specific Grav and temp
- Thread starter jazztap10
- Start date
scsinet
Active Member
Do you know if your refractometer is ATC (Automatic Temperature Compensating)?
Many are.
If not, here are some conversions.
http://www.lumcon.edu/education/stud...se/SGTable.pdf
Many are.
If not, here are some conversions.
http://www.lumcon.edu/education/stud...se/SGTable.pdf
bang guy
Moderator
Originally Posted by jazztap10
http:///forum/post/3187702
So it occurred to me that I should have to adjust the measurement I get for specific gravity from my refractometer at room temp for 80 degrees (tank temp). Specific gravity changes with temperature right? I haven't been able to find any conversion charts for it. Any ideas?
Refractometers cannot measure Specific Gravity. They measure Salinity. Salinity doesn't change significantly with temperature.
http:///forum/post/3187702
So it occurred to me that I should have to adjust the measurement I get for specific gravity from my refractometer at room temp for 80 degrees (tank temp). Specific gravity changes with temperature right? I haven't been able to find any conversion charts for it. Any ideas?
Refractometers cannot measure Specific Gravity. They measure Salinity. Salinity doesn't change significantly with temperature.
tank a holic
Active Member
bang -
my meter reads salinity on one side and SG on the other....
I understand it actually reads salinity but they have it marked so you can read the equivilent SG..... I think that's what the OP is reading
mine also is ATC
my meter reads salinity on one side and SG on the other....
I understand it actually reads salinity but they have it marked so you can read the equivilent SG..... I think that's what the OP is reading
mine also is ATC
bang guy
Moderator
Originally Posted by tank a holic
http:///forum/post/3187848
bang -
my meter reads salinity on one side and SG on the other....
Marketing. It has a long history. Salinity is what you should look at, ignore the S.G. scale.
http:///forum/post/3187848
bang -
my meter reads salinity on one side and SG on the other....
Marketing. It has a long history. Salinity is what you should look at, ignore the S.G. scale.
scsinet
Active Member
When referring to saltwater fish tanks, technically, salinity is the more accurate measurement and thus what everyone "should" use. I'm as guilty as the next guy, I always refer to sg over salinity.
To be honest, you make a good point. When considering specific gravity vs. salinity for normal saltwater tank operation, it probably doesn't make that big of a deal. Even if you are using a test calibrated to 60F and your tank is 80F, it's only going to make a difference of about 0.002 in SG from one temperature extreme to the next, and most saltwater livestock can tolerate these differences. Stability is more important that a few 0.001 one way or another.
But in hypo, I would expect it can make a difference, since those miniscule differences make a real impact on the outcome of the treatment... hmmm...
To be honest, you make a good point. When considering specific gravity vs. salinity for normal saltwater tank operation, it probably doesn't make that big of a deal. Even if you are using a test calibrated to 60F and your tank is 80F, it's only going to make a difference of about 0.002 in SG from one temperature extreme to the next, and most saltwater livestock can tolerate these differences. Stability is more important that a few 0.001 one way or another.
But in hypo, I would expect it can make a difference, since those miniscule differences make a real impact on the outcome of the treatment... hmmm...
bang guy
Moderator
Originally Posted by jazztap10
http:///forum/post/3188013
Okay, if I'm supposed to be looking at salinity, what salinity am I going for? Also, how come everyone refers to specific gravity when discussing hyposalinity, when the use of a refractometer is crucial? Thanks!
Most of the animals we keep come from waters with a salinity between 35ppt and 37ppt. From that I would consider 35ppt to be the minimum. If you have Gulf animals off of Mexico or Florida then slightly lower should be fine. Stability being a bit more important that the actual number.
For hyposalinity 14ppt is effective for killing invertebrates.
http:///forum/post/3188013
Okay, if I'm supposed to be looking at salinity, what salinity am I going for? Also, how come everyone refers to specific gravity when discussing hyposalinity, when the use of a refractometer is crucial? Thanks!
Most of the animals we keep come from waters with a salinity between 35ppt and 37ppt. From that I would consider 35ppt to be the minimum. If you have Gulf animals off of Mexico or Florida then slightly lower should be fine. Stability being a bit more important that the actual number.
For hyposalinity 14ppt is effective for killing invertebrates.