Digital Refractometers: What's your experience?

[Alexusmc]

I use the Milwaukee MA887 and so far, so good.

 

[Adamantium]

I have the Hanna HI98319, which is awesome for a quick reading, but I found it to be off by about 3PPT, even with multiple calibrations. Kind of annoying, but now I just measure to 32.4 to get 35.2 saltwater haha

I confirmed this using multiple other methods, including the Tropic Marin High Precision Hydrometer.

 

[SDJustin]

1. What's your experience with Digital Refractometers? Tell us what you like about them!1
My first digital refractometer was the Milwaukee MA887. I was getting a margin of error of +=0.002 which was too wide for me. It could be bad testing protocol on my part (not waiting for temperature no normalize?)

My second digital refractometer was the Misco Palm Abbe. #PA203. They now have a newer model specifically targeting aquariums, the #PA203X. It measures out to 0.0001, with a +- of .0005. This means I get VERY repeatable readings that hover between 1.0263 and 1.0268 when I have my salinity *just right*

I ALSO have 2x Tropic Marin hydrometers. I consider these my reference. They are great, but it takes me a while to fill up the large beaker with saltwater and float the hydrometer. The Palm Abbe takes 10 seconds tops.

The reason I was so crazy about salinity is that I was doing continuous auto water changes. If the input and output aren't perfectly balanced it's easy to drift salinity if you aren't watching it closely. I've since given up on continuous auto water changes for this reason. I tried the Neptune DOS, the Ecotech Versa, and the Kamoer FX-STP pumps and couldn't get any of those to be 'trustable' enough. I've since just reverted to weekly water changes using tubing and the Sicce Ultra Zero Utility pump. It takes about 30 minutes start to finish but is a no mess, no bucket solution.

@Randy Holmes-Farley, I don't trust my Neptune 'in water' conductivity probe, (although I do it up and running and acurate-ish right now) so never thought of using that kind instrument (conductivity/TDS) for critical testing. You've opened my eyes a bit, maybe I'll check it out!

 

[Randy Holmes-Farley]

@Randy Holmes-Farley, I don't trust my Neptune 'in water' conductivity probe, (although I do it up and running and acurate-ish right now) so never thought of using that kind instrument (conductivity/TDS) for critical testing. You've opened my eyes a bit, maybe I'll check it out!

I'm not a fan of leaving them in the water 24/7, but conductivity meters are how chemical oceanographers most often measure (and even define) salinity

 

[HJ99]

Preparing to mix our first batch and have a Hanna Checker in the BRS shopping cart. As a few others have said, my eyes aren't as good as they used to be..... along with a lot more for that matter. LOL My wife has been pushing not to skimp on this project and end up buying twice so I don't want to get something I'll have trouble reading. Seems plenty have them with no issues.

 

[Sunny in Miami]

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!



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?

I own one and it works well as long as the lense is cleaned with RODI water afterwards. I had an issue with wrong reading due to not cleaning the lense. This is my first recractomefer I use. Years ago I used one of the swing arm ones and it was not very reliable.

 

[Bruce Burnett]

Preparing to mix our first batch and have a Hanna Checker in the BRS shopping cart. As a few others have said, my eyes aren't as good as they used to be..... along with a lot more for that matter. LOL My wife has been pushing not to skimp on this project and end up buying twice so I don't want to get something I'll have trouble reading. Seems plenty have them with no issues.

I don't know about the Hanna but I used a Milwaukee for years. I expect it to be the same clean the lens well before and after each test. I made sure mine was kept in the case and would not get banged around. I would occasionally check it with calibration fluid and it was always right on. Almost never had to calibrate. The TM floating hydrometer is a good one to use or compare with. It is calibrated at 77 degrees but requires you use a tall glass or beaker.

 

[Karen00]

I have a digital salinity pen (with temp compensation) that I paid about $40 for. It's made by AZ but I bought it from a company on Amazon. It was a bit cumbersome to calibrate but once I figured that out it's easy to do now. It's calibrated with conductivity solution. I will add a caveat that I still have to verify it's accuracy. Fortunately I don't have corals yet or any creatures that are overly sensitive to salinity changes. I had purchased a regular refractometer to verify the pen but it was lost in Amazon shipping and I haven't reordered it yet. Now that we're out of lockdown in Toronto I will just bring some water to my LFS to test. I will say that I have peace of mind with the pen in so far as there has been no drift when mixing up new salt. Meaning... it took 1/3 cup of salt to get to my target in 6L of water at 70 degrees (I have cooler water creatures) and after three months of using it it's still exactly 1/3 cup of salt to reach my target. If I started needing a lot more salt or a lot less under the same conditions to reach my target or I started getting wildly different readings when checking my tank I would have tossed the pen in the garbage.

The same manufacturer also makes a conductivity pen and TDS pen. I keep reading conductivity is more accurate so I might pick up one of those.

 

[MarineBiologist!]

I use the MA886 Seawater Refractometer by Milwaukee and LOVE it! It is extremely accurate and I've only had to calibrate it twice in FOUR YEARS!! As long as you rinse it off with a little RO/DI after each use, you should not have problems with inaccurate reads. It also has three modes to read PSU, ppt and S.G. I suppose it comes with a higher price tag compared to your basic hydrometer, but seeing that digital read and 'knowing' that's what it is and it isn't "around" 1.025 is just so much easier. Plus, you only need a drop or two of the water you want to test to get a result

 

[Peter Houde]

2. Do you own a digital refractometer and if not would you ever consider using one in the future?
Yes, I have the MIlwaukee MA887. I also have the Tropic Marin floating hydrometer as my "master" and check/calibrate against it.

1. What's your experience with Digital Refractometers? Tell us what you like about them!
Love it! Easy, fast and consistent. Not quite as fast as the pen style but we're splitting hairs and I also have a salinity probe (Apex) to monitor day-to-day. (which is calibrated to read the same as the TM & Milwaukee) Since the Milwaukee is calibrated to 0 you can use different levels of 'cleanliness' to get the readings to line up with the hydrometer (distilled/RoDi, etc). I check it against the TM about every other water change or so. Haven't needed to re calibrate it again yet (months).

EDIT: What I don't like about it is it only reads 3 decimal places in SG mode (eg: 1.026 or 1.025 SG) and no decimal in ppt mode (eg: 34 or 35 ppt). 1.026 could be anywhere from 1.0255 & 1.0264). So it's mostly only for quick checking for anything out of whack. The salinity probe reads 1 decimal in ppt (eg: 34.8) and the TM hydrometer reads 4 decimals in SG (eg:1.0262) so it's covered.

Precision means nothing without accuracy. Your Milwaukee is only accurate to +/- 0.002.

 

[Peter Houde]

2. Do you own a digital refractometer and if not would you ever consider using one in the future?
Yes, I have the MIlwaukee MA887. I also have the Tropic Marin floating hydrometer as my "master" and check/calibrate against it.

1. What's your experience with Digital Refractometers? Tell us what you like about them!
Love it! Easy, fast and consistent. Not quite as fast as the pen style but we're splitting hairs and I also have a salinity probe (Apex) to monitor day-to-day. (which is calibrated to read the same as the TM & Milwaukee) Since the Milwaukee is calibrated to 0 you can use different levels of 'cleanliness' to get the readings to line up with the hydrometer (distilled/RoDi, etc). I check it against the TM about every other water change or so. Haven't needed to re calibrate it again yet (months).

EDIT: What I don't like about it is it only reads 3 decimal places in SG mode (eg: 1.026 or 1.025 SG) and no decimal in ppt mode (eg: 34 or 35 ppt). 1.026 could be anywhere from 1.0255 & 1.0264). So it's mostly only for quick checking for anything out of whack. The salinity probe reads 1 decimal in ppt (eg: 34.8) and the TM hydrometer reads 4 decimals in SG (eg:1.0262) so it's covered.

Precision means nothing without accuracy. Your Milwaukee is only accurate to +/- 0.002.

 

[Butcher333]

why 20 times? Weight your salt next time you make salt water and you'll be able the salinity near enough correct with just one or two corrects.

I started weighing my salt a while ago too. It is a lot easier to get you right in the ballpark. Weight is how I prepare my additives too. Cups per gallon isn’t very precise, so I make 1 molar solutions of each so I can precisely know how many milliliters to dose based off the reef calculator.

 

[RalphTech]

No because they're too expensive.



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

That's the one I use. To me, Na is an important parameter to log.

 

[Randy Holmes-Farley]

That's the one I use. To me, Na is an important parameter to log.

Na? Salinity?

 

[Jeff Kohlmann]

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.

What is a ‘regular’ one...? Glass hydrometer, cheap plastic pointers as car battery ones with the squeeze bulb?

 

[Jeff Kohlmann]

waste of money.
swing arm hydrometer works fine.

I’ve used swing arms in the past... they’re all junk. You can get 4 different readings from sticking bubbles. You get what you pay for. Accuracy costs. Try a glass hydrometer if digital is too costly

 

[sp1187]

I’ve used swing arms in the past... they’re all junk. You can get 4 different readings from sticking bubbles. You get what you pay for. Accuracy costs. Try a glass hydrometer if digital is too costly

cost isn't an issue with me. wasted money is.
when I test against the lfs and get the same number, except the one time when the lfs digital was out of calibration and it was way off.
tap it shake the bubbles out.
rinse in RO after use.
swing arms work fine.

 

[moreef]

I have the green one from Milwaukee. It it so much easier than anything else I have used.

Me too and have used it for years with no issues. I just clean it with rodi after each use.

 

[stravelstead]

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.

How do you recalibrate

 

[Reef.]

How do you recalibrate

test a known 35ppt solution (home made is the best ) then adjusted the screw on the top till the blue line reads 35ppt.