Do Hanna Checkers have different colour LEDs?

[BeanAnimal]

I find this all very interesting. Don't get me wrong, I want to love the checkers and did at first until I ran into problems and started really paying attention to the result. That is why I am looking at other options or workflows. I am waiting on GHL to get the kinks worked out of the ION-D and for it to go back in stock. I have high hopes for it, but those may be optimistically misplaced.

 

[taricha]

That is why I am looking at other options or workflows.

Check this page on iorodeo.

Tutorials - IO Rodeo Blog

Tutorials are project-based posts and step-by-step guides on ways to make or use open source tools in science investigations.

blog.iorodeo.com

It has write-up on nitrate, phosphate ammonia and nitrite. Step by steps for making standards, choosing different test kits, and measuring absorbance with the best LED available for those particular jobs. I think it's what you're hunting for.