Can we use colorimeter to increase reading accuracy in water tests?

Zuuu

New member
It is not always easy to read water test results correctly. Even the same color shown to different people may result in different readings, as different people often see the same color a little differently.

There are devices named colorimeters, which can convert colors to numeric values. If i understand it correctly, they just determine color of the solution and then convert it to some numeric value. For example a set of Hanna colorimeters: http://shop.hannainst.com/products/checker-colorimeters.html
But their colorimeters require test solutions (chemicals), that are not cheap.

But maybe colorimeter can be used also for other vendors? I wonder if following is possible:
1) Buy some colorimeter.
2) Prepare "colored" water using your preferred test vendor (I assume you already have test kit from some vendor like API, Seachem, etc.)
3) In addition to reading approximate value with your eyes, use colorimeter to determine precise numeric value.
4) Use some reference table created by community to convert number from step #3 to Nitrates, phosphates, etc (depending on what you've been testing).

For example, reference table could look something like
Code:
Vendor    Colorimeter Value    Nitrates
API       12                    1             
API       38                    10
Seachem   ...
etc.

Similar reference table for Phosphates, and other parameters we are testing.

Benefits:
- more precise and consistent reading of test results. No more guessing
- continue using test solutions from the vendor you trust

But this approach will not work if one colorimeter cannot measure multiple colors. For example Hanna sells different colorimeters for different parameters, and that makes me think that one colorimeter can't measure different colors.

What are your thought on this?
 
I guess Elos and another company that makes something called the iDip are making colorimeters that tie in with your smart phone and Apps installed on them. I'm looking forward to that kind of development. Otherwise I wouldn't trust many of the color checking apps as they seem to vary and some of these test kits have very slight deviations in shades of a color.
 
People have calibrated colorimeters to use with test kits. It should work if you can find appropriate standard solutions to make the chart. You will need to find a colorimeter that is sensitive in the color range that the chemicals produce, as well, which is one reason why there are different colorimeters for different tests. Hach does sell multi-parameter meters, though.

I wouldn't trust a phone camera yet to do the testing, but it might work well enough. You could try.
 
I use the ultra low PO4 Hanna Checker for measuring color of many different vendor kits. The Hanna reader needs a calibration curve for each kit. Kits that involve forming precipitates (e.g., API NH3) or gas bubbles (e.g.,Salifert NO3) are difficult to implement.

I have also had good luck using my iPad (or iPhone) digital camera and a free colorimeter app to provide a color number for any colored test solution. With a calibration curve, I can match the color number to a ppm.

I have shared information on this subject on this forum. Happy to share more details and lessons learned.
 
I use the ultra low PO4 Hanna Checker for measuring color of many different vendor kits. The Hanna reader needs a calibration curve for each kit. Kits that involve forming precipitates (e.g., API NH3) or gas bubbles (e.g.,Salifert NO3) are difficult to implement.

I have also had good luck using my iPad (or iPhone) digital camera and a free colorimeter app to provide a color number for any colored test solution. With a calibration curve, I can match the color number to a ppm.

I have shared information on this subject on this forum. Happy to share more details and lessons learned.

Please do........I'm interested in both
 
Thanks a lot to everyone for your input and suggestions! Will try camera app and colorimeter.
 
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