So that your salinity!

[jakub]

lets start off by saying i'm crazy when it coms to the basic perimeters Sal,PH and BIO.

last weekend one of my friends asked me to check his Sal with my Milwaukee so I did, his Sal was 1.028 when it was suppose to be 1.025..... so i asked him what did you use to calibrate your refractometer? "calibrate right from eBay" Jesus Christ that solution read out at 1.030 on my end.

I use Milwaukee and apex solutions to calibrate. I zero out with my RODI or Milwaukee water and then test with Apex and Milwaukee.

I'm currently out of Apex solution
so with all that said my Sal IS dot on.


This scenario made me wander who can we trust to provide us with accurate test solution? This is what I have to start. BRS with " refractometer calibration solution" I ordered 2 bottles.

Bottle#1

Bottle#2

Baby O's water

I just bought 5 more brands of solutions today. so we'll see.....

 

[TheEngineer]

It's kind of a problem, right? If you can't trust your calibration fluid, then what? I'm having an issue with my pH probe and wondering if it is the calibration fluid or the sensor.

You could make your own salinity calibration fluid with Randy's method. I'm skeptical of accuracy there too though.

 

[Randy Holmes-Farley Verified Community Expert]

It's kind of a problem, right? If you can't trust your calibration fluid, then what? I'm having an issue with my pH probe and wondering if it is the calibration fluid or the sensor.

You could make your own salinity calibration fluid with Randy's method. I'm skeptical of accuracy there too though.

If you have an accurate scale, it will be accurate.

 

[TheEngineer]

If you have an accurate scale, it will be accurate.

Haha, that's my point! Can I trust my scale? Who calibrated the scale? It's like you have to go to NIST to be able to trust anything!

 

[choff]

Great, add this to my list of things that keep me up at night.....

 

[michellejy]

I had Pinpoint that was bad. I calibrated and thought my salinity was 35 PPT on the dot. It was actually 40.

 

[Randy Holmes-Farley Verified Community Expert]

Depending on what you are calibrating, you may need to be careful to calibrate under the same lighting and at the same temp that you will use for tank water.

Calibration solutions that are allowed to evaporate will lead to falsely low salinity readings for the tank water.

If you use a controller, it is CRITICAL that the temp probe also be in the calibration solution, or that you otherwise tell the unit the exact temp of the standard.

 

[Bdog4u2]

Haha, that's my point! Can I trust my scale? Who calibrated the scale? It's like you have to go to NIST to be able to trust anything!

Good scales are easy to calibrate

 

[TheEngineer]

Good scales are easy to calibrate

But then you have to trust that the calibration weights are accurate. How do you test those!?

 

[Bdog4u2]

But then you have to trust that the calibration weights are accurate. How do you test those!?

By weighing something in which you already know said weight. For small scales nickels weigh 4.8 grams

 

[TheEngineer]

By weighing something in which you already know said weight. For small scales nickels weigh 4.8 grams

Do they though!? This is Archimedes's crown all over again! (I'm just being dramatic by the way) It's frustrating that even with the right "steps" you could wind up with a wrong result because one of the links in the chain was bad.