Instant ocean hydrometer accuracy?

[Reef man 89]

How would you go about calibrate them?

 

[MaiReef]

No calibration, just good cleaning of hydrometer. Mine seems to work well for 3 years compared to the LFS refractometer.

 

[cobraz]

I had two one was correct and the other off by 6 as well..I just bent the swing pin allittle till it matched my other one which was spot on with my refractomer...but they do vary if you have an instant ocean one. Seen this when I worked at a local shop years ago.

 

[Randy Holmes-Farley Verified Community Expert]

How would you go about calibrate them?

I explained that a few posts earlier. Use the standard fluid I posted or other fluid you know the salinity of, and then:

" If the hydrometer reads higher or lower than 1.0264, then the aquarist can just imagine the scale on the hydrometer to be shifted up or down, and shift all other readings taken with it by the same amount, just as for a standard floating hydrometer."

 

[Tristan]

The instant ocean hydrometer is pretty accurate and I've been using it for over a year now. I've borrowed my friend's refractometer and compared it against the hydrometer and the hydrometer was spot on. So I still use it as I don't have a need to get a refractometer.

 

[klp]

I used an instant ocean hydrometer for years with no issues. Checked it against a glass floater at the time. Kept both clean with RODI and had 2 or 3 instant ocean hydrometers in case one failed. I am not advocating them but with care, like refractors, they can be used. Refractors can be off as well and need to be checked for calibration so there is no perfect magic bullet. Randy has another excellent write up that will be a great help as well whatever you use.

 

[fragit]

In my opinion don't trust them. Years ago in my last tank before I had a refractometer I used 2 of them. I would use them both every time I checked salinity, get different reading and average them out. Well, it bit me in the behind and I crashed my tank. Investing in equipment like a refractometer is a must IMO. They are affordable, can be calibrated, and when your talking about the very media that our livestock lives in, they are invaluable. I say spend the $$$$ and just get one!

 

[brandon429]

how did anyone get through the 90s

 

[klp]

how did anyone get through the 90s

or the 70's and 80's

 

[Randy Holmes-Farley Verified Community Expert]

or the 70's and 80's

They invented high quality floating glass hydrometers in the 1600's, if not earlier. They were probably more accurate than hobby refractometers. lol

 

[Sm51498]

They invented high quality floating glass hydrometers in the 1600's, if not earlier. They were probably more accurate than hobby refractometers. lol

They are super accurate. much harder to use accurately though home brewers seem to manage just fine. I used glass hydrometers for years because it used to be that a refractometer was 100 dollars and a appropriate glass hydrometer was only 15. Those were the years when I used odno florescents. reefing as a broke college student

 

[MD11drvr]

Same issues here. A decade ago I used an IO Hydrometer and never had an issue. 10 years later, I'm getting back in the hobby and starting from scratch, I buy a new IO Hydrometer and an Easywin Aquaculture Refractometer with ATC. I cannot believe the difference in readings between the two. The IO hydrometer will read 1.029-1.030 while the refractometer will read a steady 1.025. I'm going with the refracometer!

 

[Nano sapiens]

Swing-arms are very quick and convenient to use, but to trust that the reading is accurate right out of the package is not a good idea. However, it's easy to simply compare the swing-arm reading with a known standard (I checked against a trusted LFS that had 2 working digital refractometers in-house) and adjust for the difference (if any).

I've been using them for over 30 years now and see no need for a refractometer (not to say they aren't a good tool).

 

[vlangel]

hydrometers are all ive used for 16 yrs and wont ever need a refract, my swingarms are taken care of as mentioned above. every few years ill calibrate them to the LFS refract and its 1 point off on the high side, but very consistent and my reefs don't care. so, ill never buy a refractometer what worked in 2001 still good for my tiny reefs.

Its also good for my seahorse tank. I have never used a refractometer and I've been doing saltwater for 20 years. Like Brandon I get mine calibrated with a lfs every so often and its been fine.

 

[brandon429]

Let the record stand that when I got my notification response I was not expecting another person to condone nonrefraction heh.

My swingarm is so old the .023 is rubbed off and I just estimate somewhere in the middle of the rub

 

[vlangel]

Let the record stand that when I got my notification response I was not expecting another person to condone nonrefraction heh.

My swingarm is so old the .023 is rubbed off and I just estimate somewhere in the middle of the rub

Yes that is true. And actually I am not so much being negative about refractometers as I am merely saying that a hydrometer has worked well for me as long as I have been in saltwater. I think each person should use the instrument that they are comfortable with.

 

[brandon429]

Yep. I bet the majority nowadays don't even start with hydro swingarm

I see tons of refraction misreads on posts, calibration issues. They're no guaranteed homerun much like bubble misreads for the hydros. I find hydros to always be off from an accurate refract, but, given good sample prep technique I do not find hydros to ever deviate from that mark. Mine always read low compared to refracts but it was within acceptable marine ranges.

 

[Tautog]

I use a large hydrometer that floats, with temp gauge, cheap, easy to read, very accurate. Just don't drop them, they break easy

 

[five.five-six]

All measurement systems in common use by hobbies are not without their problems. A refractometer measures refractive index and there are many compounds in tank water that can influence refractive index. Magnesium has about 10X the influence on the refractive index of water as does sodium chloride.

Randy's post on makeing a referance solution is really the key.

The dificulty will be mesure in the exact quantity of sodium chloride, I use a ammo reloading scale.

 

[five.five-six]

I explained that a few posts earlier. Use the standard fluid I posted or other fluid you know the salinity of, and then:

" If the hydrometer reads higher or lower than 1.0264, then the aquarist can just imagine the scale on the hydrometer to be shifted up or down, and shift all other readings taken with it by the same amount, just as for a standard floating hydrometer."

In that post you specified Mortins, would a salt water mix be suitable?