Best Refractometer?

j.falk · 04/14/2018, 11:29 AM

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 · 04/14/2018, 11:53 AM

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 · 04/14/2018, 11:57 AM

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 · 04/14/2018, 02:57 PM

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 · 04/14/2018, 03:51 PM

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 · 04/14/2018, 04:56 PM

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/milwa...actometer.html

j.falk · 04/14/2018, 04:57 PM

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 · 04/14/2018, 06:07 PM

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

kmbyrnes · 04/15/2018, 10:51 AM

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 · 04/15/2018, 12:00 PM

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 · 04/15/2018, 07:09 PM

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

04/14/2018, 11:29 AM	#1
j.falk Registered Member Join Date: May 2017 Posts: 632	Best Refractometer? 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?

04/14/2018, 02:57 PM	#4
hkgar Registered Member Join Date: Oct 2002 Location: Dewitt MI Posts: 5,051	The best one is the one that is properly calibrated. What were the readings of each? Quite likely within the margin of error. __________________ Gary 180 gallon, 40 gallon sump, 3 250 W MH + 4 80W ATI T5's, MTC MVX 36 Skimmer, Apex controller Aquamaxx T-3 CaRx Current Tank Info: A 2 Barred Rabbitfish, Red Head Salon, Yellow/Purple, McMaster Fairy, Possum, 2 Leopard Wrasses, Kole, & Atlantic Blue Tangs, 2 Percula Clown, 3 PJ and 1 Banggai Cardinalfish , Swallowtail, Bellus and Coral Beauty Angels

04/14/2018, 03:51 PM	#5
j.falk Registered Member Join Date: May 2017 Posts: 632	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. Last edited by j.falk; 04/14/2018 at 04:12 PM.

04/14/2018, 06:07 PM	#8
Bent I got nothin' Join Date: Nov 2004 Location: The anals Posts: 6,420	I’m not sure why everyone things these things are not going to have a margin of error. __________________ Quitters never lose. [QUOTE=CStrickland]Who gets mad at a starfish?[/QUOTE] Current Tank Info: 75g DT, 30G refugium, 10g chaeto tank, 50g stock tank basement sump

04/15/2018, 10:51 AM	#9
kmbyrnes Registered Member Join Date: Aug 2013 Location: Mesa AZ Posts: 2,055	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. __________________ 125g Mixed Reef 5/26/2015; 350 Butterfly Dominated FOWLR 11/26/2015 - 11/17/20217 & 07/31/18 to ??? ; 100g Mixed Reef 11/16/2013 to 06/16/2017 Current Tank Info: Too small

04/14/2018, 11:53 AM	#2
Uncle99 Crab Free Zone Join Date: Sep 2017 Location: Ontario, Canada Posts: 2,906	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.

04/14/2018, 11:57 AM	#3
j.falk Registered Member Join Date: May 2017 Posts: 632	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.

04/14/2018, 04:56 PM	#6
sus Premium Member Join Date: Nov 2007 Location: Arvada Colorado Posts: 606	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/milwa...actometer.html

04/14/2018, 04:57 PM	#7
j.falk Registered Member Join Date: May 2017 Posts: 632	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.

04/15/2018, 12:00 PM	#10
Volcmreefer Registered Member Join Date: Mar 2006 Location: Milton, FL Posts: 346	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.

04/15/2018, 07:09 PM	#11
rocsec1 Registered Member Join Date: Jul 2012 Location: Medina oh Posts: 1,782	I also use the digital model. I find it much easier to use.