Digital Refractometers: What's your experience?

revhtree · Mar 30, 2021

For today's QOTD I would like to hear about your experiences with Digital Refractometers! If you don't have experience I would still like to hear your thoughts and if you ever have plans to try one out! Let's talk about it today!

From Hanna: "The HI96822 Digital Refractometer eliminates the uncertainty associated with mechanical refractometers by measuring the refractive index to determine the salinity of natural and artificial seawater including brackish, ocean water or saltwater aquarium."

1. What's your experience with Digital Refractometers? Tell us what you like about them!

2. Do you own a digital refractometer and if not would you ever consider using one in the future?

X-37B · Mar 30, 2021

I own one but dont use it much anymore.
I prefer the TM floater for SG.

Arabyps · Mar 30, 2021

1. What's your experience with Digital Refractometers? Tell us what you like about them! I use one when mixing new saltwater. I like the ease of use and clear read-out.

2. Do you own a digital refractometer and if not would you ever consider using one in the future? I own the Hanna HI98319 unit.

HI98319 Marine Salinity Tester

Designed for Simple Aquarium Salinity Testing Hanna Instruments HI98319 Marine Salinity Tester measures electrical conductivity (EC) to determine the salinity of natural and artificial seawater. Within seconds, the salinity and temperature are measured, and then using the temperature reading...

www.bulkreefsupply.com

lpsouth1978 · Mar 30, 2021

I just got one a few weeks ago and have been VERY happy with it so far. It is so fast and much easier to get an accurate measurement. I don't think I will be going back to my standard refractometer anytime soon, though I still have it.

tamanning · Mar 30, 2021

I have a regular one for now it gets the job done. I guess I'm more worried about other measurements for now but at some point I'd like to have one.

AJsReef · Mar 30, 2021

I've had a Milwaukee MA887 for about 8 years and love it, no complaints with my Apex probe either

sp1187 · Mar 30, 2021

waste of money.
swing arm hydrometer works fine.

piranhaman00 · Mar 30, 2021

All the digital refractometers have such a wide error.

I use the Hanna conductivity when mixing saltwater to check if I am close and then confirm with veegee. That being said, I have used the Hanna for about six months now and only calibrated one time and it is still within 0.001 so I am happy with it

Randy Holmes-Farley · Mar 30, 2021

I cannot see any reason to use it.

IMO, It is marketed to reefers who have convinced themselves that refractometers are good, and so a digital one is easier and better.

Hanna claims it is only accurate to ±2 PSU; ±2 ppt

So in essence, it cannot distinguish 33 from 37 ppt.

Conductivity meters are far more accurate, even from Hanna: ±1 ppt for 0.0 to 40.0 ppt, for much less money.

KrisReef · Mar 30, 2021

Great question, and timely in my case

1. What's your experience with Digital Refractometers? Tell us what you like about them!

I used one for the first time two weeks ago. I took in a water sample (in a bucket with frags) and saw the LFS Milwaukee salinity meter setting on the counter so I after getting permission I sampled my water and it was "perfect" according to the shop owner.

2. Do you own a digital refractometer and if not would you ever consider using one in the future?

I would consider using one but I don't own one. I have used the same Sea Test swing arm for many years and it never runs out of battery power. I've taken it on vacation with me and checked water thickness at many reef locations and it's consistent. I just have to remember where it's supposed to point at to know the salinity is correct.

kaylajoy · Mar 30, 2021

No because they're too expensive.

Randy Holmes-Farley said:
IMO, It is marketed to reefers who have convinced themselves that refractometers are good, and so a digital one is easier and better.

Not to derail too much, but what is your opinion on refractometers like these for reefing VS. the hobby ones?

Frogspon · Mar 30, 2021

sp1187 said:
waste of money.
swing arm hydrometer works fine.

Well that is patently false. They die over time. IF you have used it for more than a few months I doubt yours is giving you an accurate reading. Maybe consistent, but not accurate. They are intended to teach kids how to read salinity, nothing more.

fryman · Mar 30, 2021

1. What's your experience with Digital Refractometers? Tell us what you like about them!
I used a manual refractometer for awhile and figured it was the best option, until I got a digital one. It is faster and easier, has very consistent readings and easier to re-calibrate

2. Do you own a digital refractometer and if not would you ever consider using one in the future?
I own a MIlwakee MA887

stanleo · Mar 30, 2021

I don't seem to have any issue with my refractometer as long as I calibrate it every month. So I can't justify the expense.

fryman · Mar 30, 2021

Randy Holmes-Farley said:
I cannot see any reason to use it.

IMO, It is marketed to reefers who have convinced themselves that refractometers are good, and so a digital one is easier and better.

Hanna claims it is only accurate to ±2 PSU; ±2 ppt

So in essence, it cannot distinguish 33 from 37 ppt.

Conductivity meters are far more accurate, even from Hanna: ±1 ppt for 0.0 to 40.0 ppt, for much less money.

in my experience conductivity meters were far more finicky (poor repeatability) & also time-consuming to calibrate. Also the electrodes needed to be maintained/cleaned regularly, while refractometers need basically no maintenance. Maybe they've gotten better over the years?

If it really had poor accuracy I see your point, but I regularly check my digital refractometer against reference salinity solution and it's always spot on. Couldn't say the same for my old conductivity meter, which seemed to drift over time and thus needed to be re-calibrated often. So my refractometer just seems more practical.

fryman · Mar 30, 2021

Arabyps said:
1. What's your experience with Digital Refractometers? Tell us what you like about them! I use one when mixing new saltwater. I like the ease of use and clear read-out.

2. Do you own a digital refractometer and if not would you ever consider using one in the future? I own the Hanna HI98319 unit.

HI98319 Marine Salinity Tester

Designed for Simple Aquarium Salinity Testing Hanna Instruments HI98319 Marine Salinity Tester measures electrical conductivity (EC) to determine the salinity of natural and artificial seawater. Within seconds, the salinity and temperature are measured, and then using the temperature reading...

www.bulkreefsupply.com

FYI the instrument in that pic appears to be a conductivity meter, not a refractometer.

JosephM · Mar 30, 2021

When I first got into the hobby I used the Milwaukee one that everyone loves and had horrible luck with it. I calibrated it and everything and it would give me a different reading back to back. It was a horrible experience. I now use the TM floating hydrometer for 1/4 the price and love it

mistergray · Mar 30, 2021

Arabyps said:
1. What's your experience with Digital Refractometers? Tell us what you like about them! I use one when mixing new saltwater. I like the ease of use and clear read-out.

2. Do you own a digital refractometer and if not would you ever consider using one in the future? I own the Hanna HI98319 unit.

HI98319 Marine Salinity Tester

Designed for Simple Aquarium Salinity Testing Hanna Instruments HI98319 Marine Salinity Tester measures electrical conductivity (EC) to determine the salinity of natural and artificial seawater. Within seconds, the salinity and temperature are measured, and then using the temperature reading...

www.bulkreefsupply.com

Does it work really well? It's much cheaper than the one posted by the OP.

Randy Holmes-Farley · Mar 30, 2021

fryman said:
in my experience conductivity meters were far more finicky (poor repeatability) & also time-consuming to calibrate. Also the electrodes needed to be maintained/cleaned regularly, while refractometers need basically no maintenance. Maybe they've gotten better over the years?

If it really had poor accuracy I see your point, but I regularly check my digital refractometer against reference salinity solution and it's always spot on. Couldn't say the same for my old conductivity meter, which seemed to drift over time and thus needed to be re-calibrated often. So my refractometer just seems more practical.

What actual devices did you use?

The same manufacturer (Hanna) of both devices (their digital refractometer in Rev's first post here and their inexpensive conductivity meter) claims the conductivity meter is more accurate (which presumably includes repeatability as part of that specification)

My Orion Model 128 conductivity meter COULD NOT be calibrated, so it never took any time to calibrate. Over the nearly 20 years I used it, it never drifted MORE THAN THE EQUIVALENT OF 0.2 PPT, and never needed cleaning. imo, They only need cleaning if you leave them in the tank water 24/7 (I do not advise that). An RO/DI rinse after each use precludes any need for maintenance.

I will say I am not a fan of conductivity probes on aquarium controllers that are left in the water 24/7. For whatever reason, that seems to lead to many problems.

I do also think it worth upgrading from the cheapest conductivity meters like the Hanna 86822 to better quality devices (like used Orion models on ebay with 4 electrode probes).

FWIW, I've seen quite a few folks complain about accuracy of the Milwaukee digital refractometer.