Salinity drop 0.5 ppt per day

[AgentKooper]

I used the cleaning technique the previous answer mentioned and the reader showed something totally off like 38 ppt. So now I am 99% sure it was a failed maintenance on my salinity reader. I have a tropic marin glass tube hydrometer on the way.

When you checked your Hanna salinity meter with the Hanna solution, was it often way off? If not, I'm wondering how cleaning the device would, by itself, result in such a wildly high reading.

I check my Hanna meter against the calibration solution every month or two, and it's rarely more than 0.1 or 0.2 off (I believe the margin of error is +/-0.1 ppt). I don't bother to calibrate if it reads the calibration fluid at 34.9-35.1 ppt.

I don't clean the device other than rinsing it in fresh water occasionally and wiping off the electrodes. I realize the best practice is probably to clean it more often, but am I wrong in assuming it's functioning correctly given what I've described?

 

[Quentin05]

When you checked your Hanna salinity meter with the Hanna solution, was it often way off? If not, I'm wondering how cleaning the device would, by itself, result in such a wildly high reading.

I check my Hanna meter against the calibration solution every month or two, and it's rarely more than 0.1 or 0.2 off (I believe the margin of error is +/-0.1 ppt). I don't bother to calibrate if it reads the calibration fluid at 34.9-35.1 ppt.

I don't clean the device other than rinsing it in fresh water occasionally and wiping off the electrodes. I realize the best practice is probably to clean it more often, but am I wrong in assuming it's functioning correctly given what I've described?

I calibrated it with the solution at 35, my tank was then showing 34. I cleaned it in vinegar then acid. Tank then showed 38 without re calibrating (out of solution).

Obviously it needs to be calibrated after the cleaning but ye the probes inside were quite dirty and some black came out on the paper towel when I rinsed.

 

[AgentKooper]

I calibrated it with the solution at 35, my tank was then showing 34. I cleaned it in vinegar then acid. Tank then showed 38 without re calibrating (out of solution).

Obviously it needs to be calibrated after the cleaning but ye the probes inside were quite dirty and some black came out on the paper towel when I rinsed.

What did it read the calibration solution at before you actually calibrated it (prior to cleaning)?

 

[Quentin05]

What did it read the calibration solution at before you actually calibrated it (prior to cleaning)?

I did not, but my tank was reading 34.4 before calibration and 34 after calibration. 38 after cleaning, no recalibration to gove you an idea.

 

[Ziggy17]

The only advantages of the TM hydrometer are cost, and that, assuming it was originally manufactured correctly, it cannot be miscalibrated by the user.

great point, and that’s what drew me to it. It’s only $40, and it’s 100% maintenance free as long as I don’t break it.

In this hobby, there’s inherently loads of maintenance to do and it’s very easy to throw good money at bad money. For me, the hydrometer alleviates salinity testing from the above mentioned.

 

[Sam7]

No roller, it is a JBJ 45, it is AIO. My wild guess is bad salinity checker but it is weird that it shows a constantly dropping salinity rather than just an off reading. I might just invest in the Tropic Marin big glass tube tbh.

I dont believe the hanna salinity meter is very accurate.....least not when i tested a friends out

 

[Randy Holmes-Farley Verified Community Expert]

I dont believe the hanna salinity meter is very accurate.....least not when i tested a friends out

Like most salinity devices, proper calibration is the key. :)

 

[exnisstech]

I've owned 2 of the Hanna testers and they both ended up in the trash. They always ready 0.002 low when calibrated using Hanna fluid following their directions. I tried different packs of calibration fluid etc etc. Sure I could have added 0.002 to my measurement but I didn't trust them since the calibration was always wrong. A reliable conductivity isn't in my budget so I use a TM hydrometer and then use that to check the calibration on two refractometers. I used to use Randy's diy calibration fluid prior to purchasing the TM hydrometer.

 

[AgentKooper]

I've owned 2 of the Hanna testers and they both ended up in the trash. They always ready 0.002 low when calibrated using Hanna fluid following their directions. I tried different packs of calibration fluid etc etc. Sure I could have added 0.002 to my measurement but I didn't trust them since the calibration was always wrong. A reliable conductivity isn't in my budget so I use a TM hydrometer and then use that to check the calibration on two refractometers. I used to use Randy's diy calibration fluid prior to purchasing the TM hydrometer.

They were always 0.002 low compared to a hydrometer?

 

[exnisstech]

They were always 0.002 low compared to a hydrometer?

Always compared to a hydrometer or a calibrated refractometer. Its not uncommon from the info I've gathered.

 

[AgentKooper]

Always compared to a hydrometer or a calibrated refractometer. Its not uncommon from the info I've gathered.

Interesting. I'll have to get a hydrometer. My Hanna checker has always been extremely consistent (and consistent with the Hanna checker my LFS uses) but I've never had a way to check its accuracy (I didn't see any reason to trust a calibrated refractometer over the calibrated Hanna checker). My tanks look good so I've never really worried about it, but I'd like to know if the checker is off.

 

[Randy Holmes-Farley Verified Community Expert]

Always compared to a hydrometer or a calibrated refractometer. Its not uncommon from the info I've gathered.

That suggests to me a calibration problem. Did you ever use a standard that was not theirs?

 

[exnisstech]

That suggests to me a calibration problem. Did you ever use a standard that was not theirs?

The only way I could get an accurate reading was to calibrate using water of a known salinty that i confirmed using a TM hydrometer and or calibrated refractometer. Then it would start to drift after a week or so. The convience just wasn't worth the risk for me. I mix a batch of water every week and use a TM hydrometer to confirm it's 1.025 at 77 degrees. I then use that water to calibrate my refractometers so I can use them for spot checks during the week.

 

[Randy Holmes-Farley Verified Community Expert]

The only way I could get an accurate reading was to calibrate using water of a known salinty that i confirmed using a TM hydrometer and or calibrated refractometer. Then it would start to drift after a week or so. The convience just wasn't worth the risk for me. I mix a batch of water every week and use a TM hydrometer to confirm it's 1.025 at 77 degrees. I then use that water to calibrate my refractometers so I can use them for spot checks during the week.

Not sure how you could fail if you used an actual 35 ppt conductivity standard, but I understand the drift would be a concern.

FWIW, lots of sellers of standards seem to get them wrong somehow. Not sure if that applies to the Hanna standard or not.