I just set up a monitor and it does things a little different then i am use to. I have always measured my salinity by specific gravity with numbers like (1.026) and so on. my new monitor measures the conductivity and gives numbers like 53. Since i don't completely understand the relationship between the two i also don't know the conversion. today i have a reading of 58.1 but i can't tell if its to high or not. any help would be appreciated. thanks
conductivity = specific gravity?
- Thread starter rixhater
- Start date
If that is real, it is quite high. What device did you use and did you calibrate it?
Here's a table from one of my articles relating conductivity to specific gravity:
Table 1.� Specific gravity, conductivity, and refractive index as a function of salinity of seawater. The darker blue rows represent the range usually encountered in the open ocean.
Salinity (PSU)......Specific Gravity at 25° C......Conductivity (mS/cm; 25° C)
0......1.0000......0
30......1.0226......46.2
31......1.0233......47.6
32......1.0241......49.0
33......1.0249......50.4
34......1.0256......51.7
35......1.0264......53.0
36......1.0271......54.4
37......1.0279......55.7
38......1.0286......57.1
39......1.0294......58.4
Here's a table from one of my articles relating conductivity to specific gravity:
Table 1.� Specific gravity, conductivity, and refractive index as a function of salinity of seawater. The darker blue rows represent the range usually encountered in the open ocean.
Salinity (PSU)......Specific Gravity at 25° C......Conductivity (mS/cm; 25° C)
0......1.0000......0
30......1.0226......46.2
31......1.0233......47.6
32......1.0241......49.0
33......1.0249......50.4
34......1.0256......51.7
35......1.0264......53.0
36......1.0271......54.4
37......1.0279......55.7
38......1.0286......57.1
39......1.0294......58.4
JHawlz9989
New member
Randy, I've got a sort of related question: How often do you have to recalibrate your monitor? Have you discovered over the years that it is more reliable and precise, or is it just something that the chemist in you enjoys? When you mix saltwater, is salinity checked with a monitor or refractometer?
Josh
Josh
This was measured by my Apex controller pm2 module. It has not been calibrated as i am under the impression it doesnt require it brand new but will after some time passes.
So if it is accurate (and it may be, but I do not know for sure), then I'd lower the salinity. It is easy to buy some Pinpoint 53 mS/cm fluid, or make your own if you have a good balance, and check it.
The conductivity meter I use is an old Orion model 128 conductivity meter. It is fairly sophisticated, and it never varies. When I check it in a true 35 ppt seawater standard with a conductivity of 53.0 mS/cm, it always reads 53.8 mS/cm, and it is not able to be adjusted. It also reads a bit high in a 30 mS/cm commercial standard, so I always just subtract a bit from the reading.
I also use this for a rough check of new salt water, although I do not match it exactly to the tank because I do my water changes slowly and continuously and can adjust the relative in and out flow rates if needed.
Rploaded
New member
!caution!
It absolutely must be calibrated upon receipt. Also until you connect a temp probe to that module the readings will dance all over.
Contact Paul at Neptune systems for help setting this up! Do not go changing your salinity etc until you do.
I have my temp probe connected to the base module. Does it make a difference if its in base module or in pm2?
Rploaded
New member
You should leave that probe in the base....... You should purchase a second temp probe 30$ and hook that to the pm2. Then set the temp offset and your condx readings will not float..... Great tool!! If you have questions email Paul at Neptune and he can walk you through the setup..... Also pickup some packets of calibration solution. I check mine once a month. It's a 2$ piece of mind.... Good luck
Ya when you have a reef tank there is a little too much money invested for me not to spend a extra few bucks on a extra probe. i think ill order it and some calibration fluid as well as some extra pH calibration fluid and ill call then so i have everything prepared. Not to mention i am still working on figuring out my network issues with some other really great members. I must say i am extremely pleased with how helpful all the members are, thank you.
question. what exactly does it do when you have the 2nd probe and you mentioned something about "off setting" them?
