Accuracy of TM High Precision Hydrometer

[LadyTang2]

I know from one of Randys articles that standard hydrometers are better than swing arm but how would this TM standard hydrometer stack up against a decent refractometer in terms of accuracy? Pretty close or?

 

[Dragon52]

Can't answer that for you, I used to use one like this but kept getting dropped & broke so I went to a meter type + easier on the eyes.

 

[LadyTang2]

Can't answer that for you, I used to use one like this but kept getting dropped & broke so I went to a meter type + easier on the eyes.

You mean a swing arm?

 

[Dragon52]

You mean a swing arm?

No, something like this.

HI98319 Marine Salinity Tester

Designed for Simple Aquarium Salinity Testing Hanna Instruments HI98319 Marine Salinity Tester measures electrical conductivity (EC) to determine the salinity of natural and artificial seawater. Within seconds, the salinity and temperature are measured, and then using the temperature reading...

www.bulkreefsupply.com

 

[Kaboobie]

You can easily test it's accuracy by putting it in pure water and seeing if it's off or at 1.0. Then if you wish to be doubly sure measure it in a salinity calibration solution make sure the solution and water are at the correct temperature or adjust the result for temp using calculator or table available online.

 

[Crabby48]

I think most refractometers accuracy is .002 and the Hanna memo previous post is .0005. I can tell you my Hanna reads .002-.003 lower.

 

[Randy Holmes-Farley Verified Community Expert]

I know from one of Randys articles that standard hydrometers are better than swing arm but how would this TM standard hydrometer stack up against a decent refractometer in terms of accuracy? Pretty close or?

Both will be adequate if properly used, which includes calibration for the refractometer and checking the accuracy of the hydrometer at least once.

 

[LadyTang2]

Both will be adequate if properly used, which includes calibration for the refractometer and checking the accuracy of the hydrometer at least once.

Thanks Randy, and the hydrometers really don't need calibration right, they pretty much stay accurate over the years?

 

[Rybren]

I would imagine that if you allowed crud to build up on the hydrometer then the reading would be off. If you kept it clean, then I suspect that it would be fine for many years.

 

[K7BMG]

I always wondered a couple things with the hydromiter.

Does temprature effect it?
How long should it be in the water before reading?

I recently purchased the Tropic Marin Hydromiter.
I did not think about this untill I recieved it.
Looking at it I realized that the scale is a paper or plastic straw inserted into the neck.
Can this move? I have to assume its secured but alas it did not match my salinity of my other two units.

So now I have a raised eyebrow.
I was under the impression that a high quality Hydromiter is or should be the is all benchmark.

 

[LadyTang2]

I always wondered a couple things with the hydromiter.

Does temprature effect it?
How long should it be in the water before reading?

I recently purchased the Tropic Marin Hydromiter.
I did not think about this untill I recieved it.
Looking at it I realized that the scale is a paper or plastic straw inserted into the neck.
Can this move? I have to assume its secured but alas it did not match my salinity of my other two units.

So now I have a raised eyebrow.
I was under the impression that a high quality Hydromiter is or should be the is all benchmark.

Regarding temp, yes there is a chart to convert, it will read correct at 77 degrees, if you are at ie 80 then you can use the chart.

I saw some instructions that were pretty specific on the TM site.

I would like to see a comparison with digital hanna, refractometer, hydrometer done several times for funzies.

 

[Randy Holmes-Farley Verified Community Expert]

It can be miscalibrated when made, or possibly the calibration paper might move.

in any case, checking it with a 35 ppt solution appropriate for a hydrometer is easy.

Reef Aquarium Salinity: Homemade Calibration Standards by Randy Holmes-Farley - Reefkeeping.com

http://reefkeeping.com/issues/2004-06/rhf/index.htm

 

[X-37B]

I have both and use the refrac 95% of the time.
If I get a weird reading I use the TM. The refrac I calibrate before each use, every time.
Just turned off pumps and checked with TM and they are so close im good.
My brs refrac has been in use for 3 years now.

 

[K7BMG]

I have not had the time to do the testing and comparison.
But I kight have the chance this weekend.
As I now have four units to measure Salinity.
TM Hydromiter
Milwaukee
BRS ATC Refractomiter
Hanna

The two that have matched mostly are the Milwaukee and the BRS.

In the end I know a stable salinity using the same instrument is the best.
If its bit high or a bit low but stable everything will adapt and thrive.

 

[Hans-Werner]

Please take care to read the hydrometer at the water surface. I prefer to view from slightly below the water surface. So I can sea the water surface very sharp and clear and I see the ring around the hydrometer where the water surface is hoisted. Here I read the lower water level, not the upper Edge.

 

[K7BMG]

Please take care to read the hydrometer at the water surface. I prefer to view from slightly below the water surface. So I can sea the water surface very sharp and clear and I see the ring around the hydrometer where the water surface is hoisted. Here I read the lower water level, not the upper Edge.

I will look at both.

 

[Randy Holmes-Farley Verified Community Expert]

I will look at both.

I show the proper way to read a hydrometer here:

Chemistry and the Aquarium: Specific Gravity: Oh How Complicated!

This month, Randy explains and reviews specific gravity.

reefs.com

Figure 4. A Tropic Marin hydrometer showing the meniscus rising to about 1.0260, but the actual reading is about 1.0265.