WTB: Pinpoint Salinity Calibration Fluld

[africangrey]

If you have a bottle which you can spare, I would like to buy it from you to calibrate my refractometer. I just discovered the refractometer which I have been using for the past 5 years is underestimating the salinity level after using the lab made (Randy's reciepy) 53ms/cm fluid, 3.65g/96.35mL of RO/DI. 35ppm reading at 40ppm. so for all the salt water I made in the past 5 years has been 30 ppm instead of 35 ppm, if I made the calibration fluid correctly.

 

[jkreefer]

you can use distilled water and it will test out at exatly zero

 

[tropoasis]

Unfortunately, that is not always the case when testing a refractometer.

The only way to be sure is to use the calibration fluid.

 

[mdt178]

jeff,
that's not the proper way to check a refractometer.

africangrey,
I think I have the same problem. No wonder calcium levels have always been low! Mine is more like 31-32 ppm. I'm going to order the fluid from Marine Depot in my next order, but if my reef has been running all this time, I think it can survive a couple more months.

 

[africangrey]

There is a big thread in Chemistry section where most cheapo refratometers made by the one and only company in China (blue handle) are under estimating the salinity values when using the calibration fluid. So for those who have been using the refractometer to make up fresh SW, your salinity level might have been 1.021 instead of 1.026 if the it's not properly calibrated. All this time for the past 3 years I thought my refratometer is more accurate than the swing arm type, but this might not be the case if RO/DI water is used as ruler.

 

[Newreeflady]

africangrey,

Do you have a refractometer or a Pinpoint salinity monitor (a conductivity meter)?

I have the Pinpoint conductivity meter, and it comes with a solution to calibrate with. The solution itself is supposed to be reuseable as long as you do not contaminate it.

Drs. F&S has some solns for sale, but none of them say 53mS, so i'd ask Randy in the chemistry forum if it is what your looking for as he is very knowledgeable with this equipment.

You are welcome to come by and use my 53mS soln, although I can't guarantee accurace, it's working for me (I think.) But, if you find the soln, pls post back so I know where to buy.

thx,
Angela

 

[Unarce]

I always buy mine directly: http://www.americanmarineusa.com/

 

[Newreeflady]

gtk. thx