What color is "red" and "blue" in the CH test?

[Solvangswimmers]

Sorry that sounds odd but I put my 25 ml of pool water in, add 20 drops of R-0010, then 5 drops of R-0011 and the sample is Fuschia pink

I start dripping in the R-0012 and after 2-3 drops its noticably turning purple

Around 10 drops its a slowly become a deep blue-ish purple, so I THINK I have a CH of 100 ppm, but I could be way off.

Is there a better test? I like a definitive titration where it goes colorless, or to an opposite color!

 

[PaulR]

Sounds more-or-less right; because you have to go 20-30 sec between drops it can be hard to tell whether the blue is actually still changing. But I usually get a more bluish blue.

Check out Taylor's web page about the CH test:
http://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=35
--paulr

 

[Solvangswimmers]

Stolen from Paul's Link:

5. I got a purple endpoint instead of a blue endpoint when I did a hardness test. What happened? There are metals interfering with the test, most likely ions from algaecides, pipes, or even the source water itself. To avoid this problem, add five or six drops of titrant to the sample before adding the buffer and indicator, then proceed normally with the test. Always include the number of drops of titrant added at the beginning of the test­­ when counting the total number of drops required to reach the endpoint.

Have you tried this?? I sure hope I dont have metals or ions from algaecides! We just did a total drain and refill for high CYA and we have only PVC pipes.

Does anyone start with RED after buffer and indicator or is it common to start PINK

 

[Beez]

Mine starts off pink and ends in a pale violet.

 

[PaulR]

You can try doing the six-drops-of-titrant-first method and see if that changes anything. Unless you have well water, it's unlikely that a 100% refill would have significant metals in it. Another possibility is impatience, that you weren't really quite at the true endpoint. The CH test is the most tedious because of the 20-30 seconds of swirling between each drop (and don't shortcut that part).

I have no personal experience with alternative colors, sorry!
--paulr

 

[Solvangswimmers]

well I didn't know about the 20-30 seconds of swirling between drops! I learn something new here every single day

I will try to do the test properly from now on, even if it starts as pink with floaties

no, we dont have well water.

 

[Beez]

well I didn't know about the 20-30 seconds of swirling between drops! I learn something new here every single day

I will try to do the test properly from now on, even if it starts as pink with floaties

no, we dont have well water.

Good luck...it ain't easy...I usually start out with the 20-30 seconds, but by the end of the test I'm lucky to make it to 3!!! That's why I just ordered the magnetic stirrer...can't wait!


Dave

 

[CaOCl2]

Here are the starting and ending indicator colors when titrating the Taylor standard CH solution:

Start:

End:

 

[Solvangswimmers]

Thanks for the pictures!

my start color is the same as yours. My end is not that blue but I have not been swirling anywhere near as long as 20 sec between drops.

I have a magnetic stirrer at work - I am going to have to try it.

 

[JasonLion]

The colors will not always be the same. Various things, notably very high FC levels and metals in the water, can change the appearance somewhat. The pictures that CaOCl2 posted are what most people should be seeing most of the time. But it won't always look like that.