Are hydrometers accurate

[THE REEF WHISPER]

Glass one's I was looking into to buying a Tropic Marin High Precision Hydrometer I have been using a glass one for about a year and a half now I don't use anything else it's great lot of people say it's More accurate because you don't have to calibrate it

 

[Fish Fan]

The Tropic Marin glass hydrometer specifically is thought to be very accurate. It's helpful to have a 500mL graduated cylinder to use it in, and the water temp should be at 77F

 

[THE REEF WHISPER]

I don't think it matters about the temp because you can but it in a calculator to see whats it at and but the temperature in it will do the math

 

[Euphylliaphyle]

Just to clarify, because "accurate" means different things to different people:
If you are looking for the difference between the hydrometer reading and the "true" value as a point estimate, then you can make a known concentration saline solution and use it as the operational definition of "true" value. See the fine write-up by @Randy Holmes-Farley: https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/
If you are wondering if you will get the same result in repeated tests, that's simple enough: Just repeat the test procedure several times (using aquarium water is fine for this - no calibration solution is needed.) This is known as repeatability rather than accuracy.

In my experience, the Tropic Marin hydrometer is fine by either measure. ymmv

 

[RabidDragon]

Accuracy is the proximity of measurement results to the accepted value.
Precision is how close repeated measurements are to each other.

 

[TangerineSpeedo]

I have two TM Hydrometers. They are .0007 off from each other. Now at first glance you may feel thats not bad... that is very close to 1ppt different. I tend to not run 35ppt or 1.0265 because it is too close to the margin of error. But I am very consistent with my target salinity when I mix my salt.
Even the stated accuracy of the TM is only .001. Nothing in our affordable aquarists line is accurate. With that in mind, just create a buffer.

 

[atoll]

 

[Jay Hemdal Verified Community Expert]

Glass one's I was looking into to buying a Tropic Marin High Precision Hydrometer I have been using a glass one for about a year and a half now I don't use anything else it's great lot of people say it's More accurate because you don't have to calibrate it

I wrote an article about salinity / specific gravity measurements:

https://www.reef2reef.com/ams/measuring-salinity-specific-gravity-in-aquariums.867/

 

[THE REEF WHISPER]

Just to clarify, because "accurate" means different things to different people:
If you are looking for the difference between the hydrometer reading and the "true" value as a point estimate, then you can make a known concentration saline solution and use it as the operational definition of "true" value. See the fine write-up by @Randy Holmes-Farley: https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/
If you are wondering if you will get the same result in repeated tests, that's simple enough: Just repeat the test procedure several times (using aquarium water is fine for this - no calibration solution is needed.) This is known as repeatability rather than accuracy.

In my experience, the Tropic Marin hydrometer is fine by either measure. ymmv

Cuz I was looking in to get one. I mean I've been using mine for the past year and a half and everything's good but I was just wondering if they're accurate because I interested to get another one that brand. I got a Refractometer on Amazon and it had really really good reviews and I got it and it was just like it worked for like a few weeks and after that like I calibrated it every single day and then it just started like getting all different levels. And it was so confusing and I'm like I can't do this anymore and I don't want to drop like $150 on a refractometer. But I've been seeing things about the glass hydrometer and those seem to be pretty good. People say that they're inaccurate, but I've been reaching out to local fish and reef stores and they've been saying that it's an old fashioned WAY OF TESTING. People have been using them for like 40 years and never how to replace it. They never really get out of calibration and people rather use that than the regular like digital ones

 

[Malum Argenteum]

I messed up my reef fairly seriously with a refractometer calibrated with bad commercial calibration solution. Yeah, I could've double checked it. Yeah, I could've double-point calibrated with RODI. But the thing with the TM is, it doesn't need calibrating, and so is more foolproof. Sometimes I'm a fool, so this is a good thing. I understand that some people have never experienced user error in their lives, so this may not apply to them.

It is also a lovely tool -- honest and simple, just basic physics. They don't make much stuff like that anymore, and that's a shame.

 

[jimk60]

I messed up my reef fairly seriously with a refractometer calibrated with bad commercial calibration solution. Yeah, I could've double checked it. Yeah, I could've double-point calibrated with RODI. But the thing with the TM is, it doesn't need calibrating, and so is more foolproof. Sometimes I'm a fool, so this is a good thing. I understand that some people have never experienced user error in their lives, so this may not apply to them.

It is also a lovely tool -- honest and simple, just basic physics. They don't make much stuff like that anymore, and that's a shame.

Anyone who tells you they've never experienced user error in their life will lie about other things also! LOL

 

[THE REEF WHISPER]

Just to clarify, because "accurate" means different things to different people:
If you are looking for the difference between the hydrometer reading and the "true" value as a point estimate, then you can make a known concentration saline solution and use it as the operational definition of "true" value. See the fine write-up by @Randy Holmes-Farley: https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/
If you are wondering if you will get the same result in repeated tests, that's simple enough: Just repeat the test procedure several times (using aquarium water is fine for this - no calibration solution is needed.) This is known as repeatability rather than accuracy.

In my experience, the Tropic Marin hydrometer is fine by either measure. ymmv

I want people's opinions. I don't want AI

 

[THE REEF WHISPER]

I messed up my reef fairly seriously with a refractometer calibrated with bad commercial calibration solution. Yeah, I could've double checked it. Yeah, I could've double-point calibrated with RODI. But the thing with the TM is, it doesn't need calibrating, and so is more foolproof. Sometimes I'm a fool, so this is a good thing. I understand that some people have never experienced user error in their lives, so this may not apply to them.

It is also a lovely tool -- honest and simple, just basic physics. They don't make much stuff like that anymore, and that's a shame.

Anyone who tells you they've never experienced user error in their life will lie about other things also! LOL

That's crazy lol that's too good

 

[Reef Jedi]

Personally for accuracy I use a Refractometer. Only time I use a hydrometer is when I want a quick glance. I’ve done this for over 20 years and haven’t had any issues as long as you keep your refractometer calibrated properly.

 

[Euphylliaphyle]

I want people's opinions. I don't want AI

Not sure what you may be implying, if anything, quoting my post and then stating, "I don't want AI." But just for the record, I wrote every word myself, and off the top of my head. You see, I spent many years first as a Certified Quality Engineer (ASQ-CQE) and then as a Quality Engineering Manager. This was in automotive and consumer products industries. Part of the responsibilities of both roles was design and/or oversight of gage and test equipment calibration and measurement systems statistical analysis. I may know very little about reefkeeping, but I do know this subject. The terminology may vary somewhat between disciplines, but principles are the same.

 

[Sam7]

I think if you keep it consistent it will be fine. Even if your off by a fraction either way doesnt really matter much.

I ran reefs at 23 -26 and even less years ago.....still worked. Who is right...nobody

 

[THE REEF WHISPER]

True I'm in high school I started when I was 14 low. The hobby so much

 

[THE REEF WHISPER]

I want people's opinions. I don't want AI

Not sure what you may be implying, if anything, quoting my post and then stating, "I don't want AI." But just for the record, I wrote every word myself, and off the top of my head. You see, I spent many years first as a Certified Quality Engineer (ASQ-CQE) and then as a Quality Engineering Manager. This was in automotive and consumer products industries. Part of the responsibilities of both roles was design and/or oversight of gage and test equipment calibration and measurement systems statistical analysis. I may know very little about reefkeeping, but I do know this subject. The terminology may vary somewhat between disciplines, but principles are the same.

I'm so sorry for that it just sounded like it I really do apologize in my half thank you so much I really do appreciate it so much

 

[Euphylliaphyle]

I'm so sorry for that it just sounded like it I really do apologize in my half thank you so much I really do appreciate it so much

No worries! But I don't know if I should feel honored or insulted for being mistaken for AI lol! The intelligence here is meager, but it is real!

 

[THE REEF WHISPER]

Don't take it as an insult. As Me I would take it as a compliment. You're a smart person. I mean I wouldn't know lol that's why I'm asking lol I need people like you to help me lol And the thing is I do ask AI to help me with my reef tank so yeah.