Tropic marin hydrometer

[Pudgeshambley]

Has anyone had one of these not be accurate? It is not matching the refractometer I have. Used Fritz calibration liquid. Took a sample to my lfs. Bought a second bottle of Fritz calibration to make sure the other bottle wasn't bad. None of the readings have matched. My refractometer reads lower. Lfs was a little higher. Personally I trust the hydrometer but was wondering if anyone has ever had any issues with the hydrometer. The measurements on the hydrometer don't go low enough for me to test it in RO water so wasn't sure if there was another way.

 

[Naso180!]

Not sure if it's a new hydrometer or not but they generally need to be cleaned out or replaced over time. I have several since I believe hydrometers in general are only semi reliable. Even identical, brand new.

 

[Pudgeshambley]

Not sure if it's a new hydrometer or not but they generally need to be cleaned out or replaced over time. I have several since I believe hydrometers in general are only semi reliable. Even identical, brand new.

It is a floating glass hydrometer. Nothing to clean out.

 

[Dbichler]

Your hydrometer is most likely correct

 

[Dburr1014]

Not sure if it's a new hydrometer or not but they generally need to be cleaned out or replaced over time. I have several since I believe hydrometers in general are only semi reliable. Even identical, brand new.

Why would they need to be replaced?
If keeped clean they should last maybe... Forever?

 

[PanhandleReef]

I have the Apex salinity (reads steady with only .2 fluctuation), Orion Con 6+ conductivity meter, 2 different brand refractometers, and the Tropic Marine Hydrometer. All read slightly different and I will always use the Hydrometer as my standard.

 

[Randy Holmes-Farley Verified Community Expert]

Regardless of what might or might not be accurate, if you have a scale you can check any device we use, include hobby hydrometers, using the DIY standards I detail here:

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

FWIW, it has become quite trendy for folks to claim the Tropic Marin is accurate, but many of these folks have not actually tested the accuracy with a standard, and what they really mean is it will read the same at the same temperature and water.

I'd like to see more folks test them so we can see how accurate they are and how much variation there might be. The smaller Tropic Marin I tested was quite accurate at 35 ppt. :

Temperature Corrections for Hydrometers by Randy Holmes-Farley - Reefkeeping.com

Figure 3. The Tropic Marin floating hydrometer, showing the meniscus rising to
about 1.0260, but the actual reading is about 1.0265.

 

[Dbichler]

Why would they need to be replaced?
If keeped clean they should last maybe... Forever?

He was thinking it was a swing arm hydrometer not floating glass

 

[fishgirljockey]

Has anyone had one of these not be accurate? It is not matching the refractometer I have. Used Fritz calibration liquid. Took a sample to my lfs. Bought a second bottle of Fritz calibration to make sure the other bottle wasn't bad. None of the readings have matched. My refractometer reads lower. Lfs was a little higher. Personally I trust the hydrometer but was wondering if anyone has ever had any issues with the hydrometer. The measurements on the hydrometer don't go low enough for me to test it in RO water so wasn't sure if there was another way.

You have to clean them with regular water thoroughly because overtime the salt can build up and not give you an accurate reading.