new TM Hydrometer

[Back2Reef]

Oh wow, all this time, I’ve been using Refractometer from Amazonand it says 1.026. And yes, I have calibrated it a couple weeks ago.

Well, the TM Hydrometer was delivered today and it says 1.0231 at 77F.

smh

oh well, let me do a water change.

 

[SnowyFox]

I have the opposite issue, the TM hydrometer gives me a higher value than all of my other salinity testers. Planning to mix up a reference solution sometime to confirm that the TM hydrometer is actually giving me accurate data

 

[Back2Reef]

Yeah, now I’m in doubt. But Im leaning towards the hydrometer being more correct.

I may have to get a 3rd tester.

 

[Kilman805]

I suggest trying Randy's DIY hydrometer calibration solution:
https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/

From there:
To produce a 3.714 weight percent sodium chloride solution, dissolve 1 teaspoon (6.20 grams) of Morton's Iodized Salt in 161 mL (161 g) of fresh water (making a total volume of about 163 mL after dissolution of the salt). This solution can be scaled up as desired.

I scale it up to ~2000 ml because the cylinder I use with the TM hydrometer needs ~1500 ml. Making a bigger batch also reduces the effect of errors in weighing the components. I used a smaller balance with 0.1 g precision for the salt and another balance with 1 g precision for the water. I get skeptical about measuring the salt and water in kitchen volumetric tools like measuring cups, but Randy gives those instructions too in the above link.

So scaling up proportionally, 77 g salt in 2000 g RODI water gives you the 3.714 wt% solution, which should read 1.0264 SG on your hydrometer at 77°F. If possible, make the measurement at that temperature. But you can also apply a temperature correction per: https://www.hamzasreef.com/Contents/Calculators/SalinityCorrection.php

When I did this with my TM hydrometer it was spot on. That's why it's the measurement tool I trust most.

 

[Kilman805]

Note that this recipe is for pure sodium chloride salt (table salt), not reef salt.

 

[SnowyFox]

I suggest trying Randy's DIY hydrometer calibration solution:
https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/

From there:
To produce a 3.714 weight percent sodium chloride solution, dissolve 1 teaspoon (6.20 grams) of Morton's Iodized Salt in 161 mL (161 g) of fresh water (making a total volume of about 163 mL after dissolution of the salt). This solution can be scaled up as desired.

I scale it up to ~2000 ml because the cylinder I use with the TM hydrometer needs ~1500 ml. Making a bigger batch also reduces the effect of errors in weighing the components. I used a smaller balance with 0.1 g precision for the salt and another balance with 1 g precision for the water. I get skeptical about measuring the salt and water in kitchen volumetric tools like measuring cups, but Randy gives those instructions too in the above link.

So scaling up proportionally, 77 g salt in 2000 g RODI water gives you the 3.714 wt% solution, which should read 1.0264 SG on your hydrometer at 77°F. If possible, make the measurement at that temperature. But you can also apply a temperature correction per: https://www.hamzasreef.com/Contents/Calculators/SalinityCorrection.php

When I did this with my TM hydrometer it was spot on. That's why it's the measurement tool I trust most.

This was exactly what I was planning to do, and is the same reference solution I was going to make.

 

[Jay Hemdal Verified Community Expert]

Yeah, now I’m in doubt. But Im leaning towards the hydrometer being more correct.

I may have to get a 3rd tester.

I've gone that route - using multiple devices to try and find some consensus. At the public aquarium where I was curator at before I retired, I ran ALL of our devices through a standard sample, using a lab grade glass hydrometer (25 years old), as the metric, since it was giving the most consistent, accurate reading. I then wrote correction factors on all the other devices in the building. Here is an article I wrote on that:

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

 

[Pod_01]

So the way I checked my TM Hydrometer is to take a measurement next I send sample of water to ICP lab that measures salinity and if they match up I call it a day.
So far the ICP results and TM hydrometer are inline.

Good luck,

 

[bluemon]

So the way I checked my TM Hydrometer is to take a measurement next I send sample of water to ICP lab that measures salinity and if they match up I call it a day.
So far the ICP results and TM hydrometer are inline.

Good luck,

And then you break the TM hydrometer and have to repeat the process :downcast-face-with-sweat:

My biggest achievement in my 15 years of this hobby is not ever breaking a hydrometer

 

[Pod_01]

And then you break the TM hydrometer and have to repeat the process :downcast-face-with-sweat:

My biggest achievement in my 15 years of this hobby is not ever breaking a hydrometer

I have not managed that yet…

I do ICP tests every 6 months, just to make sure water chemistry looks good. So if I managed to break it there would be opportunity to verify the replacement is good.

I do have to say, buying TM hydrometer was the best money I spend in this hobby.
Before that I had 2 refractometer, 4 calibration fluids and when measuring 4 times I got 4 different results.

 

[tritonpower]

It's $150 but I have found the vee gee STX-3 refractometer to be just as accurate as my hydrometer. FYI

 

[Tangdora]

When every I have calibrate my apex salinity probe and Hanna salinity tester I alway like to compare the numbers to my TM. Number always seem to be right in line after factoring tank temps against Randy’s conversion chart. I now use my TM as the gold standard in confirms my probe calibration was successful.

 

[Back2Reef]

I have the Brightwell Aquatics Refractometer Calibration Solution that's about 13 months old.
Does it ever expire or lose accuracy ?

I used the calibration solution again last evening and it does say that my refractometer is off. So it seems to suggest that the TM Hydrometer is accurate!

​

 

[minus9]

I have the Brightwell Aquatics Refractometer Calibration Solution that's about 13 months old.
Does it ever expire or lose accuracy ?

I used the calibration solution again last evening and it does say that my refractometer is off. So it seems to suggest that the TM Hydrometer is accurate!

​

If there's evaporation, yes. Plus, I think you need to shake that solution? Solutions that require shaking before use are terrible. The only solution I used besides making RHF's recipe is Aqua Craft, all the others were way off. With the TM hydrometer, make sure you're using the correct chart for temp correction. What you're reading on the hydrometer could be different based on the water temp.
Correction chart

 

[BeanAnimal]

When every I have calibrate my apex salinity probe and Hanna salinity tester I alway like to compare the numbers to my TM. Number always seem to be right in line after factoring tank temps against Randy’s conversion chart. I now use my TM as the gold standard in confirms my probe calibration was successful.

I built a calculator for that using the UNESCO equations of state of seawater, as well interpolated data from that table.

https://beananimal.com/tools/tropic-marin-precision-hydrometer-correction-calculator/

So the way I checked my TM Hydrometer is to take a measurement next I send sample of water to ICP lab that measures salinity and if they match up I call it a day.
So far the ICP results and TM hydrometer are inline.

Good luck,

ICP does not test salinity -- they are just doing what you are doing, measuring using a refractometer, hydrometer or using conductivity.

 

[rtparty]

The TM glass hydrometer is the gold standard IMO. I would trust it over any other hobby grade tester we have and I don’t trust salinity from any ICP company out there.

 

[Pod_01]

ICP does not test salinity -- they are just doing what you are doing, measuring using a refractometer, hydrometer or using conductivity.

I believe I wrote ICP lab that measures salinity, not that ICP measures salinity.
English is not my mother tongue so sometimes things may not sound just right…

I do believe (perhaps incorrectly) that the ICP labs that provide this service do use conductivity probes, other methods would cost too much.
The one I use stated as much, again the company does invent science “BOLUS explanation” etc… so who knows what they actually use. But the number match up.

Also I am not referring to the labs that estimate salinity based on the ions…

 

[BeanAnimal]

I believe I wrote ICP lab that measures salinity, not that ICP measures salinity.
English is not my mother tongue so sometimes things may not sound just right…

All good one way or the other. I think most people using these services don't understand that tests like Salinity, phosphate, ammonia, or alkalinity. If returned, those results are derived by the same basic test (titration, etc.) that we use as hobbyists.

I do believe (perhaps incorrectly) that the ICP labs that provide this service do use conductivity probes, other methods would cost too much.
The one I use stated as much, again the company does invent science “BOLUS explanation” etc… so who knows what they actually use. But the number match up.

Also I am not referring to the labs that estimate salinity based on the ions…

I would imagine it depends on the lab. For all we know, some could be using the same off the shelf titrations and refractometers that we use. Given that one of them claims to have access to science that defies known science, reinforces my feelings in a broader sense.


Happy Bolus Thursday
(kind of like Taco Tuesday, but different)
:)

 

[Laith]

Just as a reminder, TM hydrometers sold in Europe (I think all of Europe but not sure) measure density, not specific gravity (SG). So you need to convert from density to SG. I spent a couple of months thinking I was measuring SG until I realized...

Edited to change salinity to specific gravity.

 

[KStatefan]

Just as a reminder, TM hydrometers sold in Europe (I think all of Europe but not sure) measure density, not salinity. So you need to convert from density to salinity. I spent a couple of months thinking I was measuring salinity until I realized...

There have been others also did not know that.