Best Refractometer?

[j.falk]

I've had my water tested with 3 different refractometers this morning and all of them have said different results. What is the best one on the market that is known to give a reliable accurate reading?

 

[Uncle99]

I am hoping the difference is quite small.
I use one when I mix the salt 48 hours before the change and one just before I make the change.
Get one that comes with 35 ppt calibration fluid, I did not find a difference between the $30 and the $100.

 

[j.falk]

Yeah, I think I need to find some calibration fluid. I tested with a new ATC that was never used before, my old ATC, and then my wife's refractometer from her lab at the local hosptial...all three had completely different readings.

 

[hkgar]

The best one is the one that is properly calibrated.

What were the readings of each? Quite likely within the margin of error.

 

[j.falk]

0.022, 0.024, and 0.030 (this last test was the one done at the hospital lab)

Once we got done testing the water with each one...we then checked the calibrations with distilled water...all three tested out that they should have been accurate. So I don't know...obviously 2 of the 3 is lying...or maybe even all 3.

 

[sus]

Any refractometer will be accurate if calibrated properly, but for how long? I also don't like that temperature affects the reading. My mixing station is in the garage where the water is quite cold. I ended up buying the Milwaukee digital and it's awesome. Wish I would have bought one originally. It's really fast to use and dead on accurate. Worth every penny IMO

https://www.bulkreefsupply.com/milwaukee-digital-seawater-refractometer.html

 

[j.falk]

Disregard. I got it figured out. I didn't realize that when you calibrated it the line for the distilled water had to be on the zero line inside the refractometer.

 

[Bent]

I’m not sure why everyone things these things are not going to have a margin of error.

 

[kmbyrnes]

These things are not lab-grade instruments. There will a margin or error.

If you calibrated to 0 using RO/DI, you will likely have an error at 35 ppt.
If you calibrated at 35 ppt using reference solution, you will likely have an error at 0 ppt. It may even read less than zero.
IMO, By calibrating to the 35 ppt solution, you get the most accuracy at the target salinity. As you vary from the reference point, accuracy decreases.

 

[Volcmreefer]

Love my Milwaukee digital. You calibrate with distilled water and you are good to go. Just the $ you save on calibration fluid helps offset the cost a little.

 

[rocsec1]

I also use the digital model. I find it much easier to use.