Hanna HI98319 Accuracy - Is my tank freezing?

[trevorhiller]

I got the Hanna Temp and salinity checker for Christmas, I decided to calibrate it and check my water this morning to see how it compares to my existing devices. Obviously there were some discrepancies and now I’m looking for some advice.

I used the 35 ppt Hanna solution to calibrate the device. Just for kicks, I put a drop of the calibration solution on my Amazon refractometer and it reads about 36. The package says not for use with refractometers, so I’m not sure if that’s accurate or not. But I tested my tank water and I’m getting 33.6. The refractometer is saying 35 ppt. If the refractometer is in fact 1 ppt higher than my tank water is probably around 33.6-34.

The second discrepancy is my temperature. This is the one that really concerns me. I’ve been using an Aquaneat thermometer from Amazon since the beginning to monitor my aquarium temperature. I’ve got my heater dialed into about 79 degrees. This morning I checked the temp with the Hanna thermometer and it reads 73.2. The Aquaneat thermometer is saying 80.2 (weird, because I’ve never seen it read that high). As a third check, I tested the tank with a meat thermometer and got 73.0. Pretty close to the Hanna.

Originally, I thought my Eheim Jager heater was out of calibration because I had to adjust the red dial quite a bit to get it dialed in, but now with these results I’m thinking it’s really the AquaNeat thermometer that’s off and my tank has been too cold for weeks.

Questions-
1. Is the Hanna Salinity/temp checker reliable to adjust the tank heater to?
2. How fast should I adjust the tank temperature. 73 degrees is too low for my liking. I’d like to fix this.
3. What’s a good continuous thermometer for my tank to replace the AquaNeat
4. Can you really not use the Hanna salinity calibration solution on a refractometer? If the Hanna calibration solution should be reading 35 on the refractometer, then my refractomer is 1 ppt high and my salinity would be 33.6 on the Hanna and 34 on refractometer.

Over the last week, one of my snails has been pretty stationary on the back glass. The other two are moving around, but not as fast as I’d expect them too. This morning I found the one upside down on the sand bed dead. I suspect the water being too cold is slowing them down/killing them. Water parameters otherwise seem good.

 

[WallysWorld]

I got the Hanna Temp and salinity checker for Christmas, I decided to calibrate it and check my water this morning to see how it compares to my existing devices. Obviously there were some discrepancies and now I’m looking for some advice.

I used the 35 ppt Hanna solution to calibrate the device. Just for kicks, I put a drop of the calibration solution on my Amazon refractometer and it reads about 36. The package says not for use with refractometers, so I’m not sure if that’s accurate or not. But I tested my tank water and I’m getting 33.6. The refractometer is saying 35 ppt. If the refractometer is in fact 1 ppt higher than my tank water is probably around 33.6-34.

The second discrepancy is my temperature. This is the one that really concerns me. I’ve been using an Aquaneat thermometer from Amazon since the beginning to monitor my aquarium temperature. I’ve got my heater dialed into about 79 degrees. This morning I checked the temp with the Hanna thermometer and it reads 73.2. The Aquaneat thermometer is saying 80.2 (weird, because I’ve never seen it read that high). As a third check, I tested the tank with a meat thermometer and got 73.0. Pretty close to the Hanna.

Originally, I thought my Eheim Jager heater was out of calibration because I had to adjust the red dial quite a bit to get it dialed in, but now with these results I’m thinking it’s really the AquaNeat thermometer that’s off and my tank has been too cold for weeks.

Questions-
1. Is the Hanna Salinity/temp checker reliable to adjust the tank heater to?
2. How fast should I adjust the tank temperature. 73 degrees is too low for my liking. I’d like to fix this.
3. What’s a good continuous thermometer for my tank to replace the AquaNeat
4. Can you really not use the Hanna salinity calibration solution on a refractometer? If the Hanna calibration solution should be reading 35 on the refractometer, then my refractomer is 1 ppt high and my salinity would be 33.6 on the Hanna and 34 on refractometer.

Over the last week, one of my snails has been pretty stationary on the back glass. The other two are moving around, but not as fast as I’d expect them too. This morning I found the one upside down on the sand bed dead. I suspect the water being too cold is slowing them down/killing them. Water parameters otherwise seem good.

I don’t know the range of the Hanna thermometer but nature supplies two reasonably accurate temperature points that can be used to verify performance -the ice point and boiling point. The ice point is easier and if you’re using distilled water can be very accurate. The internet can give you lots of recommendations on how to make an ice point. The boiling point is harder because of altitude/barometric pressure. But again if you’re not looking for milliK of accuracy, it can be used to test. Test you thermometer at these two temperatures, if it gives good readings then I’d expect it to do so near tank temperatures.

 

[PeterC99]

When you have that divergent of readings, it’s very important to get a third tester. Hopefully you can borrow a friends tester for temps. If not buy a $10 digital thermometer on Amazon.

I thought my calibrated refractometer was accurate until I sent my saltwater out for an ICP test. What I thought was 35 ppm was actually 32.3. Now I use the same Hanna Temp/Salinity tester and find it gives me the most accurate results.

 

[ShakerBreaker]

I have double-checked the temperature before with a bbq meat thermometer if you have one. Worked just fine, I keep an old one in my maintenance tub in case I need it

 

[trevorhiller]

I have double-checked the temperature before with a bbq meat thermometer if you have one. Worked just fine, I keep an old one in my maintenance tub in case I need it

This is what I tried too, but it was giving me low readings as well.

I tried to do the freezing/boiling point tests with the thermometers, except I didn't boil the new Hanna because I would hate to melt the housing.

Results:

Aquaneat: Freezing 33.4 / Boiling "HI"
Weber BBQ Thermometer: Freezing 30.9 / Boiling 208.4
Hanna: Freezing 32.4 / Boiling Not Tested

I conclude that I might just be an idiot and the thermometers are all fairly accurate. I overlooked a variable in my testing....probe position. My aquaneat probe was in the rear chamber, but I was testing the Hanna and the BBQ in the front display. I didn't realize that there would be about a 5 degree difference from the rear chambers to the front display.... but this is the problem.

I'm going to slowly increase the heater over the next few days and measure the water where the fish are.

 

[homer1475]

You absolutely cannot use the Hanna calibration packets designed for the HI98319 to calibrate your refractometer. They use 2 different methods of testing.

Refractive index, and conductivity are 2 totally different ways to measure salinity, and their respective calibration packets are not interchangeable.

If your in doubt of either, it's very easy to make a standard solution with morton table salt, RO/DI, and a decent kitchen scale(search out DIY calibration solution written by @Randy Holmes-Farley ).

As far as temp goes, my hanna is spot on with my apex, and handheld cheapo aquarium thermometer I bought at petco. I have done the freezing/boiling for calibration on all three(been doing it that way for many many years, as thats how I was taught to calibrate a meat thermometer in culinary school).

 

[trevorhiller]

You absolutely cannot use the Hanna calibration packets designed for the HI98319 to calibrate your refractometer. They use 2 different methods of testing.

Refractive index, and conductivity are 2 totally different ways to measure salinity, and their respective calibration packets are not interchangeable.

If your in doubt of either, it's very easy to make a standard solution with morton table salt, RO/DI, and a decent kitchen scale(search out DIY calibration solution written by @Randy Holmes-Farley ).

As far as temp goes, my hanna is spot on with my apex, and handheld cheapo aquarium thermometer I bought at petco. I have done the freezing/boiling for calibration on all three(been doing it that way for many many years, as thats how I was taught to calibrate a meat thermometer in culinary school).

I used his recipe to make a liter of calibration solution (figuring that was a decent enough volume to account for error since I’m using kitchen scales accurate to 0.1 grams). Looks like my refractometer was a little high. Adjusting the refractometer down, gets it closer to what the Hanna is reading.

So it looks like my tank is little hypotonic, around 33 ppt.

It is odd to me though that you can’t use the one solution to test both the refractometer and the Hanna though. When I dip the Hanna in the DIY 35 ppt calibration solution, I’m getting around 37 ppt. It would be much more reassuring to my brain if it read around 35. Still curious as to why this is? For example, I mixed salt using the Hanna and got 35 ppt. I test the same water with the refractometer calibrated with the DIY solution and get 37. There’s obviously a discrepancy and I don’t know which is right, but since the Hanna is easier to use and likely more accurate than the $18 Amazon refractometer, I’m going to use it as my baseline since there’s an acceptable range for salinity anyhow. It does bother my OCD though…. Especially since I did the calibration on the refractometer and the Hanna isn’t reading the same.

 

[Cohibaman]

You absolutely cannot use the Hanna calibration packets designed for the HI98319 to calibrate your refractometer. They use 2 different methods of testing.

Refractive index, and conductivity are 2 totally different ways to measure salinity, and their respective calibration packets are not interchangeable.

If your in doubt of either, it's very easy to make a standard solution with morton table salt, RO/DI, and a decent kitchen scale(search out DIY calibration solution written by @Randy Holmes-Farley ).

As far as temp goes, my hanna is spot on with my apex, and handheld cheapo aquarium thermometer I bought at petco. I have done the freezing/boiling for calibration on all three(been doing it that way for many many years, as thats how I was taught to calibrate a meat thermometer in culinary school).

Good post!

Even though Randy’s conductivity-based calibration solution and refractive index-based calibration solution are made with the same salt, in this case sodium chloride, they are completely different (it’ll measure slightly different, so you MAY think they should read the same with each technology. It’ll drive you crazy if you think they can be used interchangeably!).

Do yourself a favor and make up two reference solutions; one for refractive index and a second for conductivity. Make sure you mark them both so you know which one you’re using.

After you’ve calibrated both instruments with their respective cal solutions, your tank water measurements should read very close on both Instruments.

 

[mdb_talon]

I conclude that I might just be an idiot

Haha. I can say about half the time my equipment does not work this is my problem also

 

[Fin]

How long did you leave the Hanna checker in the tank water? I know the one that I have takes a while to get to a maximum temp reading and all the while the temp goes up, the meter is adjusting the salinity reading. Try taking about 30 seconds to let the temp max out and then make note of the salinity reading. Hope that helps.

 

[EricR]

My Hanna digital registers temp a degree or two low if I'm going quick.
If I leave it in the water longer and just keep re-clicking to test, it eventually shows correct temp -- I just don't use it for accurate temperature checks at all, really.

For salinity, this may or may not be TRUE but just what I observed:
-- when I was calibrating with the 35ppt Hanna solution COLD (maybe low 60s Fahrenheit), the Hanna checker seemed to always register tank salinity too low by almost 1 ppt.
-- started calibrating with the 35ppt solution heated to tank temp and now the checker seems spot on (salinity) for me.

*whether or not heating the calibration solution (to tank temp) was the real solution or I have just gotten into better calibration solution packets, I can't be 100% sure but, for me, it's enough so that I always calibrate with the solution at tank temp now. (My checker holds calibration well so I mostly just check it periodically -- so far so good)

...take that with a grain of salt, I guess