How many trust these meters?

[NanoSteam]

I have the Hanna. Replaced the first one since it was not reliable. The second one has same issues. I have it laying around but almost always use a VeeGee Refractometer which is best on the market and lines up with my periodic ICP tests.

I just got a Veegee STX-3 *Chefs kiss*

 

[BryanM]

Which model do you have? My Milwaukee has always been pretty accurate. I wipe off the well after every measurement, and usually take 4-5 different measurements whenever I'm testing (each measurement takes about a second, so it's not like that's a hassle). Fill the pipette, drop in the well, measure, wipe it down, drop again to make sure I'm getting the same reading. Empty the pipette, draw in more water from a different part of the water, and test again. If it all matches then I'm golden. I've verified it against both a refractometer, and against controlled calculations (I use a scale to weigh out my salt) and it's never been meaningfully off.

I have the MA887, but will be selling it. I don't trust it.

 

[Biokabe]

I have the MA887, but will be selling it. I don't trust it.

That's the same model as I have, but different color - I think mine is much older, I bought it so long ago that I can't even find the receipt in my email. It was also $99 when I bought mine, and I see they're now going for $175. I wonder if they "upgraded" the sensor in later models, so everyone could enjoy the privilege of paying more for a worse product.

 

[mook1178]

So my day job is an application scientist for post sales support.. So when I customers saying that an instrument is not reliable, I always inquire their calibration techniques and they're reason for not being reliable. A lot of the time, the answer is I have another instrument measuring the same thing.

My first thing to start trouble shooting is calibration of both instruments, if that is good we look at precision of the instrument measurement.

I think what we see when people say a certain instrument is unreliable compared to another the are things to consider.

1. Calibration of both
2. Do the methodologies of measurement compare
3. Precision, if we take into account precision do the measurements overlap?

So what is the precision of your refractometer compared to the Hanna and Milwaukee? Is it really unreliable at that point? We're both instruments recently calibrated? Can you truly compare an analog SG to a digital SG? What are the inherent errors of each instrument? Does that make the one with larger error unreliable?

I guess my point is, do people calling the HANNA or Milwaukee unreliable, truly understand their instruments accuracy, precision, and method of measurement? Or do they just see a different value than a previous instrument and therefore it is unreliable?

I see people expressing concern of 0.2 ppt of salinity. When in reality, that is more than likely just a precision and/or accuracy difference. Accuracy can be fixed with a better calibration. Precision is not something that can usually be fixed by the user.

 

[exnisstech]

I have no issues with the Hanna salinity meter, but I also don't have other ways to test salinity. I'm measure in ppt, not SG. I just measure my tank before I mix new water and make she they match.

So you have no idea for sure what your salinty really is just what the meter reads. I couldn't reef like that. I have to have something I trust like a TM hydrometer or refractometer calibrated with fluid I trust like Randy's recipe. I guess if you trust the Hanna and it works it's good for you.

 

[Usarmy227]

First I always use a refractor meter pictured below. I calibrate my refractor meter with my RODI water that contains no salts. I don’t really rely on refractor juice.

So here are my results….
Which one do you think is right?

 

[Fish Fan]

First I always use a refractor meter pictured below. I calibrate my refractor meter with my RODI water that contains no salts. I don’t really rely on refractor juice.

So here are my results….
Which one do you think is right?

I know that guys like Randy Holme-Farley suggest calibrating a refractometer with a 35 ppt standard that's up near what your trying to measure, rather than 0 TDS RODI water, even if the refractometer's instruction say to do so. Further, RHF has suggested that some of the sore bought calibration standards can sometimes be off. For that reason, he suggests calibrating with his DIY standard solution made from ordinary Mortons table salt and a decent kitchen gram scale. I'd suggest making the solution and recalibrating, and then see what they read:
https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/

 

[mook1178]

So you have no idea for sure what your salinty really is just what the meter reads. I couldn't reef like that. I have to have something I trust like a TM hydrometer or refractometer calibrated with fluid I trust like Randy's recipe. I guess if you trust the Hanna and it works it's good for you.

It reads between 35 and 36 ppt, if it's actually 33 it's no big deal. The tank looks good and I dose alk and calcium. So really the only thing we need salinity is the osmotic pressure for the inhabitant. Salinity range then extends at that point. 32-37 ppt is likely fine for osmotic pressure. So with that said, I'm not stressing my salinity to be exactly 35 ppt, just that the water change matches to not cause stress.

No meter is that far off, unless your not calibrating.

 

[atoll]

I have had a number of hydrometers including but not limited to the Hanna, Milwaukee and rejected them all. I now have had a large Tropic Marin floating hydrometer with a similar sized measuring vial and its the best and most accurate I have found. You have to treat them carefully and the thin glass stalk can quite easily break if you are clumsy. They aren't cheap nor is the matching vial, well in the UK anyway but you get what you pay for.

 

[mcarroll]

I don't get how folks have so much trouble with salinity these days! Seems like thread after thread of this sort of thing.

Bubbles on the swing arms of our $free$ hydrometers was the only real salinity trouble to have back in the day. I guess we had it good! Speaking of back in the day...

"In my day" (including today) we (eventually) had auto-temperature-compensating refractometers come along.

Amazing!

Today a lot of people seem to have auto-self-decalibrating refractometers.

That's significantly less amazing!

And from reading this...I guess digital meters also have this (new? old?) auto-self-decalibration feature!?

Is modern gear all really this bad? ...or is this something like those Amazon reviews where you look at the 1-️ reviews and "it's the user somehow"? ....or what is it?

(Answers would be cool, but I guess these are mostly rhetorical questions. I am treasuring my refractometer more with every thread I read like this. :D)

I guess the rest of this is (still) just nerdery, but....also still on topic??

How much do we really need a device to measure salinity?

If we are consistent and reasonably accurate in measuring our water and our salt mix (can easily be done), we don't "technically" even need a salinity measurement device to make seawater correctly.

(I have calibrated, or verified calibration, on everything from five gallon buckets to 60 gallon drums. So far I'm trusting my 150's calibrations. Gram scales and accurate measuring cups are cheap.)

1/2 cup of mix per gallon of water – just be consistent and this will work.

Also, this is accurate if you want to measure even more precisely, but IMO that's "extra": https://www.hamzasreef.com/Contents/Calculators/DirectSaltCalculator.php


If you have a measurement device, even a swing-arm hydrometer, you should be able to calibrate it (if needed) based on one or more accurate mixes of saltwater. (One will do, but confirmation via repeatability is always nice!!!)

Same basic idea as RHF's DIY mentioned in post #27 while I was typing. That also should be "extra" but it will take any variance from your salt mix out of the equation. (You know folks out there would be using tiny scoops of their totally caked up bucket of salt that was left open fourteen times last summer and still expect it to make the calibration solution. So no....with those folks in mind, go with formula that works with morton's please.)

Anyway, the instrument is mostly to double check your volume/mass/weight measurements. If your system salinity is stable (eg. enclosed system w/ATO and no protein skimmer) you might theoretically even get by without one at all.

(I wouldn't choose to be without a salinity measuring device...unless they really are as bad as you all have been saying!!! No....I'm just saying about its role and our state of dependency on it, that's all.)

P.S. This is a good read if it's new to anyone looking here: https://www.reef2reef.com/ams/refractometers-and-salinity-measurement.5/
The wisdom of the article is sorta buried in the middle though:

This error [with refractomeres] is significant, in my opinion, but not usually enough to cause a reef aquarium to fail, assuming the aquarist has targeted an appropriate salinity in the first place.

This is almost more true than the chemistry/physics he talks about in the rest of the article (which is also true). :)

It's too bad no words are spent on specifics of who's distributing bunko refractometers into the hobby....."truth in advertising" is usually a pretty reliable issue to precipitate a little healthy public shaming.

 

[Tangdora]

The salinity tester has worked good in the past for me when I used it. Key to it is to calibrate it with the solution at temp tank and keep it held in the water during calibration. I now however use the apex salinity with the tropic Marin precision as occasional validation.

The ph is junk. That specific model has this weird paper on the glass probe. That your suppose to pull out when numbers get out of wack no idea why. But it never worked right for me when I stored it in solution and then tried to test. I still use Hanna but I upgraded to HI98121 which is much more precise imo

 

[mcarroll]

Holy....so chewy will auto-ship a "reef tank/koi pond" refractometer for $9. (Is that real?? It says "specially designed for saltwater..." in the first line of the description, and it doesn't look bad...it does show ATC on the chassis. )

Maybe they really are intended to be disposable?!!! Then I guess who needs it to hold a calibration? Thow it in the trash and wait for next month's auto-ship?!

BTW, I'm almost positive this is the marinedepot refractometer I have (can't find any paperwork or I'd be certain):
https://web.archive.org/web/20071017042509/http://marinedepot.com/ps_ViewItem~idProduct~MD2101.html
Dunno if anyone is still selling this unit under a different brand, but it's been a champ.

 

[00W]

 

[Gtinnel]

I have the Hanna salinity pen and absolutely hate it. Even with constant calibration it isnt consistent for me. I would be fine with the accuracy being off but I at least want it to be consistent. I bought mine used from the forum and question of it was sold because of reliability issues with that specific one.
I now use a cheap optical refractometer and my Milwaukee refractometer and trust both of them. Plus I mostly look at my Apex probe and its normally correct, but will occasionally give me wildly incorrect readings. They are so far off that I know to ignore them, I just dont let anything on apex be controlled by that probes reading.

 

[Naekuh]

You did not pull out a OG hydrometer! @00W

May as well bring out the floating one they use for BEER.
Because if its good enough for BEER its good enough for our reef tank right?

I use the Hanna... because i got a whole bunch of calibration solution on sale last time, and can calibrate it for the next 5 yrs or so.

I have a light refractometer, but i only use that if i cant find my hanna in 30 seconds.

 

[Fish Fan]

Guys, I've said this before and I'm going to say it again here - I love my Milwaukee digital refractometer, and it will have to be pulled from my cold, dead hands

Yes, I know it's not the absolute most accurate device available, but it's plenty accurate and consistent for me (I have and use the TM floating hydrometer to verify), and it's hands down the most convenient and easiest to use refractometer available, even if not "the best" solution

 

[mcarroll]

I was always jealous of this one – bigger and curvy! I have the (older?) rectangular one. (Works more or less the same. Your scale is slightly bigger I think.)

 

[NanoSteam]

This is all I knew and used for 15 years and it never failed me so I'll defend it to the bitter end.

 

[Naekuh]

i used to use these guys until i kept breaking.
wasn't kidding about if its good enough for beer, its good enough for our reef tank.

 

[KrisReef]

This is the most reliable hydrometer available for the hobbyist to test the salt density in a marine environment with.

It relies upon archimedes principle to raise the arm repeatedly according to the amount of salt dissolved in the water and does not require any internal calculations to determine how thick the water is.

Any of the meters that measure the electrical conductivity in the solution are impacted by the ion present and the liquid temperature to calculate how much salt is present. The change in water temperature or the chemical composition of the solution will affect the results that are calculated to determine the result given.

This swing arm has traveled with me to many different reefs and no matter the water temperature it has always pointed to the same location when I have “calibrated” it in the South Pacific or in the Caribbean oceans.

I had an equipment failure last week that dumped ~10 gallons of system water onto the garage floor while the automatic top off emptied ~5 gallons of RODI into the same system until it was empty. I added 10 gallons of salt water back into the system and performed an additional 10 gallons of water changing before I refilled the top off and then allowed the water level to drop to where it is replacing evaporation normally. The salinity is slightly elevated now, so I need to remove ~3 gallons of system water and let the ato replace that in order to get the salt level down to where the ocean salinity is normally at.

I don’t know what the precision is of the hydrometer but I don’t sweat the details. My dreresa clam is a bit agitated for the recent instability but it can’t tell me the numerical value of the overage either.

The simplest measure is easiest to acquire without any electrical computation to complicate the calculation, ime. Give me a floating hydrometer any day and I will be happy to use that to keep salinity stable, without having to perform any calibrations.

People who weigh their salt are on the right track but again if they are using a digital scale, there is an electrical component that complicates things.