Conductivity vs Refractometer

[Jeepjeep_0]

I have read through a few kinda similar threads, but most were older.

Need some help folks. I have the Hanna HI98319, and this is where I’m at.

I swapped over to the Hannah about 4 months ago. I calibrate it monthly with the Hannah satchets and it always calibrated flawlessly.

I test weekly with The Hanna HI98319. I test my DT water and mix water for a water change to the same specific gravity. I am ALWAYS @ 1.026 per the Hanna.

The other day I brought a sample of my water up to a reputable LFS To compare my measurements of all parameters. Everything was pretty similar but I was at awe to see they were measuring my salinity at 1.030 specific gravity using a refractometer. (LFS said they calibrate their refractometer with RODI every morning.)

I went home and pulled out my two old Refractometers, cleaned them and calibrated them with RODI as I was out of calibration fluid.

Upon testing my water I measured 1.030 on one refractometer and 1.029 on the other.

I hastily started heating fresh RODI and was going to start bringing down my salinity, but after taking a deep breath held off.

I called Hanna the next morning and spoke with a tech. He stated that results of the Hanna “conductivity” tester could not be compared with the refractometer because they were different in how they measured. He insisted Hannas was more accurate (which I would expect) and that as long as I was able to calibrate the Hanna HI98319 Without any issues I should trust the more accurate conductive reading than the other 3 refractometer readings.

Now I don’t know what my best course of action is. After reading through a bunch of threads on R2R everyone has discrepancy’s but mine seems dangerously larger than the others. On that note I have a large mixed reef of softies, LPS, & SPS as well as an abundance of fish & Shrimp and everything seems great and all colors and growth are amazing.

Any suggestions on how to proceed? I want to think this one through prior to making any rash decisions.

 

[Woodneers]

LFS shouldnt be calibrating with RODI even if it is every morning. Do you calibrate your refractometers and if so with the proper calibration solution?

 

[Garf]

Same answer on both threads LOL

 

[Jeepjeep_0]

I put my full faith in this Hannah and stopped using the refractometer. I am ordering calibration solution as we speak as I never replenished when I stopped using it.

 

[Jeepjeep_0]

Same answer on both threads LOL

Thank you sir, I posted there thinking no point in starting a new one. However I was unable to find my question embedded in that thread so I decided to make a new thread.

 

[homer1475]

Calibrating a refractometer with RO/DI is a no no, and will show unusually high salinity if done that way.

If this LFS was reputable, they should know that.

With my hanna, and properly calibrated refractometer, they give the same result.

 

[Jeepjeep_0]

Calibrating a refractometer with RO/DI is a no no, and will show unusually high salinity if done that way.

If this LFS was reputable, they should know that.

With my hanna, and properly calibrated refractometer, they give the same result.

Thank you for the feedback. I’m gonna order the solution now. I believe the cal solution I used prior came with my refractometer, what solution are you using?

 

[Garf]

On the upside, it’s easy to make you own calibration solution for a refractometer using RODI and table salt

 

[Jeepjeep_0]

I was just reading that in the last article, may try that as well while I find a calibration solution

 

[homer1475]

On the upside, it’s easy to make you own calibration solution for a refractometer using RODI and table salt

This +1000.

I use the hanna packets for the conductivity meter. I bought a huge bag of them when I bought the hanna about 2 years ago. When they are gone, I'll do the DIY method for conductivity also.

 

[Jeepjeep_0]

This +1000.

I use the hanna packets for the conductivity meter. I bought a huge bag of them when I bought the hanna about 2 years ago. When they are gone, I'll do the DIY method for conductivity also.

I have the Hannah packets for the Hanna, need to get a reference solution or make it for the refractometer.

 

[homer1475]

DIY Salinity calibration solutions

Randy, In light of another post on calibrating a conductivity meter, I decided to give it all a shot on my own system. I read through your article on DIY salinity calibration (http://www.reefkeeping.com/issues/2004-06/rhf/) and have a few questions for my simple brain. 1. Is the Brand MORTON...

www.reef2reef.com

 

[Garf]

I have the Hannah packets for the Hanna, need to get a reference solution or make it for the refractometer.

I suppose you could get the hanna calibrated. Then test your water with it. Then set your refractometer with the now known salinity of your test water. Thereby using your hanna to calibrate the refractometer.

 

[Jeepjeep_0]

Well that was my issue, the Hannah is properly calibrated per manufacturer directions and calibration solution. That’s what I’ve been using and trusting @ a constant 1.026.
I brought my water in to make comparison aT the LFS and that’s where I was told my water was measuring at 1.030.

 

[Garf]

Well that was my issue, the Hannah is properly calibrated per manufacturer directions and calibration solution. That’s what I’ve been using and trusting @ a constant 1.026.
I brought my water in to make comparison aT the LFS and that’s where I was told my water was measuring at 1.030.

It appears they have led you up the garden path.

 

[Reef.]

I put my full faith in this Hannah and stopped using the refractometer. I am ordering calibration solution as we speak as I never replenished when I stopped using it.

make your own fluid takes a couple of minutes, calibration fluid can be off, buy two bottles and you will likely get two different readings.

I was not a believer when people said you can not calibrate a refractometer with rodi, as my refractometer said to use rodi, now having bought a hydrometer, I then used a known 1.026 solution to calibrate my refractometer and sure enough it was off, when the rodi was showing it was correct.

 

[Lasse]

Hanna have special calibration fluids for their meter and there often an other for refractometers. I have noted that it is not enough to calibrate a refractometer at 0 - you need to check that it shows 35 psu (or 1.026) to with a calibration solution. If they differ - trust the 35 psu calibration point - it is more close to you real measurements. If the slope is wrong - it does not matter if your water is near to the calibration point. If you calibrate at 0 and the slope not is perfect - you get whatever as result.


There will also be a possible error if you open your calibration fluid - eveproperation will make it stronger by time. I solve that problem by sucking up the calibration fluid in a syringer. Put a cap on and store it that way. When I calibrate I just press out some fluid and put the cap back directly. There is also companies that deliver their calibration fluid in a syringer. If you use the Hanna packet - do not reuse it if you do not use everything directly - store the leftover in a syringe instead.



Sincerely Lasse

 

[Tim Olson]

I have the Hannah packets for the Hanna, need to get a reference solution or make it for the refractometer.

I really dove into this earlier this year (see thread), since I couldn't get accurate and consistent readings from any of the measurement instruments I used. I now primarily use a Hanna HI08319 Salinity Tester. The secret bullet, though was to calibrate it with TLF AccuraSea, which is pure natural sea water. I found the Hanna calibration fluid was significantly off, compared to AccuraSea and a Lab-prepared solution of Randy's formula (which was graciously provided by a fellow reefer).

So, it would be worth a try to get some AccuraSea and compare the results to with your devices.

 

[Jeepjeep_0]

I really dove into this earlier this year (see thread), since I couldn't get accurate and consistent readings from any of the measurement instruments I used. I now primarily use a HannaHI08319 Salinity Tester. The secret bullet, though was to calibrate it with TLF AccuraSea, which is pure natural sea water. I found the Hanna calibration fluid was significantly off, compared to AccuraSea and a Lab-prepared solution of Randy's formula (which was graciously provided by a fellow reefer).

So, it would be worth a try to get some AccuraSea and compare the results to with your devices.

So your using the accurasea to calibrate refractometer & just to see if your Hanna matches when you test the Accurasea solution?

 

[Jeepjeep_0]

Are you saying you calibrate your Hanna with the Accurasea?