Which salinity tool would you trust?

WrasseyReefer · Jul 21, 2023

Hi everyone,

Just want to get other people’s opinions about this. I have a hanna salinity checker that I calibrate with the Hanna salinity 35 ppt packets that expire 04/2027. I have an instant ocean hydrometer. I ordered some hydrometer calibration solution coming this week. And I have a refractomer from Amazon that was calibrated with continuum 35 ppt refractometer calibration solution that expires 05/2027. All three tools are giving me different salinities. I just did a water change and utilized the new refractometer (calibrated first) to get my water to 1.026, just slightly below the 35 ppt mark, ~34.5. The Hanna (freshly calibrated with fresh calibration packet) is giving me 31.6 = 1.0238. The instant ocean hydrometer is giving me ~ 1.0243 (slightly less than halfway between 1.024 and 1.025). I realize all of these have an accuracy range. Hanna is ±1.0 ppt ±1.0 PSU. I can’t seem to locate the accuracy of my refractometer or the hydrometer. The Hanna and refractometer are not within 1.0 ppt of each other. I’d like to know if my tank water is actually at 1.0238 or 1.026, given that it’s a decent range. I’m sure everything would be fine at either salinity, but it would be nice to know. Which tool would you trust?

Thanks for your help!

Rusty904 · Jul 21, 2023

I bought a high precision hydrometer from tropic Marin. I use this to measure my tank water, then use my tank water to calibrate all other devices (hanna, apex, etc.) with the hydrometer reading.

WrasseyReefer · Jul 21, 2023

Update: tested hanna 35 ppt calibration solution on refractometer. It measures 26 ppt = 1.0196. Poured Hanna calibration packets into hydrometer and got 1.021. So it would appear that the Hanna calibration packets are bad.

WrasseyReefer · Jul 21, 2023

Rusty904 said:
I bought a high precision hydrometer from tropic Marin. I use this to measure my tank water, then use my tank water to calibrate all other devices (hanna, apex, etc.) with the hydrometer reading.

Do you have a link to hydrometer you use?

mrpontiac80 · Jul 21, 2023

WrasseyReefer said:
Do you have a link to hydrometer you use?

High Precision Hydrometer

Ensure that your equipment is reading correctly and your aquarium is at the right salinity with Tropic Marin's High Precision Hydrometer. Many tank inhabitants are sensitive even to minor changes of the water conditions. Unfortunately as we've all experienced, salinity reading equipment as...

www.bulkreefsupply.com

In my opinion it is the most accurate tool but be prepared to receive a broken one if you order because they are fragile especially in the hands of ups or etc.

WrasseyReefer · Jul 21, 2023

Just tested hanna 35 ppt calibration solution with my Milwaukee refractometer that I zeroed with rodi, and it was 1.019. Seems these Hanna packets are bad.

Acros · Jul 21, 2023

Milwaukee MA887

Charlie the Reefer · Jul 21, 2023

Hydrometer! As a second I use ICP tested water that I calibrate my refractometer to.

dmsc2fs · Jul 21, 2023

Rusty904 said:
I bought a high precision hydrometer from tropic Marin. I use this to measure my tank water, then use my tank water to calibrate all other devices (hanna, apex, etc.) with the hydrometer reading.

This is the answer.

stoney7713 · Jul 21, 2023

Acros said:
Milwaukee MA887

I use this exclusively now. I have other test equipment but this is my go to. I zero it with steam distilled water to zero as per instructions. I use Randy's salt calibration solution for cross reference. Always been spot on.

mike550 · Jul 21, 2023

WrasseyReefer said:
Update: tested hanna 35 ppt calibration solution on refractometer. It measures 26 ppt = 1.0196. Poured Hanna calibration packets into hydrometer and got 1.021. So it would appear that the Hanna calibration packets are bad.

The Hanna salinity checker measures conductivity. So the calibration packet is set for conductivityl. Refraction and density measurements will be incorrect. But it’s not an issue with the Hanna packets

Also to answer your question about which to trust think about significant figures when measuring. Let’s just call it 1.025 for your refractometer, 1.024 for Hanna, and 1.024 for your hydrometer. The difference is 0.001 or less than 0.10% (0.001/1.024 * 100)

I think you’re fine

WrasseyReefer · Jul 21, 2023

Acros said:
Milwaukee MA887

I have that as well, and that tested at 1.025, so more similar to refractometer and hydrometer than hanna.

KrisReef · Jul 21, 2023

When I took a vacation to a Carribean reef or to a Pacific Isle I try to take my SeaTest swing arm hydrometer and dip it in a few different locations to calibrate my technique and to see what kind of water issues they are having on these reefs. The swing arm is almost level, with little variation in all of the natural settings. I used to bring it to the LFS to bother folks with it. These "plastic pieces of junk" can work fine if you have calibrated them properly.

If I wasn't so clumsy I would still have a glass hydrometer to use all the time but I generally leave it in the cabinet (somewhere) because I have broken so many of them over the years. I like the fact that the hydrometer and swing arm both have no electrical circuits to calculate the density of the water, they just float and tell us what Archimedes described with reliable precision.

As you can see, a swing arm is a thing of beauty and near perfection when used properly.

WrasseyReefer · Jul 21, 2023

stoney7713 said:
I use this exclusively now. I have other test equipment but this is my go to. I zero it with steam distilled water to zero as per instructions. I use Randy's salt calibration solution for cross reference. Always been spot on.

I will make Randy’s calibration solution to check as well.

WrasseyReefer · Jul 21, 2023

dmsc2fs said:
This is the answer.

Gonna buy one.

WrasseyReefer · Jul 21, 2023

mike550 said:
The Hanna salinity checker measures conductivity. So the calibration packet is set for conductivityl. Refraction and density measurements will be incorrect. But it’s not an issue with the Hanna packets

Also to answer your question about which to trust think about significant figures when measuring. Let’s just call it 1.025 for your refractometer, 1.024 for Hanna, and 1.024 for your hydrometer. The difference is 0.001 or less than 0.10% (0.001/1.024 * 100)

I think you’re fine

Refractometer is at 1.026, so it’s 0.002 off from Hanna and hydrometer. Just trying to determine which one is correct, but I see what you’re saying.

WrasseyReefer · Jul 21, 2023

Thanks everyone for your feedback. I think making Randy’s salinity calibration solution is a great idea. I can use that to test the hydrometer, the refractometer, the Milwaukee, and the Hanna. I realize whether it’s 1.024 or 1.026, it’s fine, but I’d prefer to be at 1.026. Haha so if I can help it, I’d like to know. I’ll also buy the high precision hydrometer. I’m a perfectionist and control freak to a fault, so…

mike550 · Jul 21, 2023

WrasseyReefer said:
Thanks everyone for your feedback. I think making Randy’s salinity calibration solution is a great idea. I can use that to test the hydrometer, the refractometer, the Milwaukee, and the Hanna. I realize whether it’s 1.024 or 1.026, it’s fine, but I’d prefer to be at 1.026. Haha so if I can help it, I’d like to know. I’ll also buy the high precision hydrometer. I’m a perfectionist and control freak to a fault, so…

If you want that level of confidence in your measurements make sure to adjust for temperature on your hydrometer and refractometer.

I would also suggest the Milwaukee digital meter and the Tropic Marin hydrometer

WrasseyReefer · Jul 21, 2023

mike550 said:
If you want that level of confidence in your measurements make sure to adjust for temperature on your hydrometer and refractometer.

I would also suggest the Milwaukee digital meter and the Tropic Marin hydrometer

I have the Milwaukee digital meter. It read 1.025, so between the hydrometer reading and the refractometer reading. I’m going to order the tropic marin hydrometer.