TF 100 CH test

HouTex

LifeTime Supporter
Mar 7, 2011
413
Houston, Texas
When performing the CH test (with a 10 ml sample and using 3 drops of the 0011L) my sample barely turns violet/red. It's extremely faint. Is this normal? It's very hard to tell when the color changes to blue and when it does change you can barely tell. The reagents are about 18 months old, but they acted this way right out of the box.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
What happens if you do the test with a 25ml sample and 5 drops?

I never see a dark red, but it is pretty obvious when it turns blue.

Has it stained the bottle?
R-0011L is calcium indicator, an organic dye used to provide the red/blue color. It should be a deep blue color. If the dye stains the plastic bottle it is stored in, it has gone bad.
 

HouTex

LifeTime Supporter
Mar 7, 2011
413
Houston, Texas
Because of my high CH I have never tried the 25 ml sample. I'll give it a try. The R-0011L is pretty thick but I don't think it really stains the bottle. Again, it came that way and it hasn't changed consistency or how it colors the water sample since the time it was purchased.
 

Patrick_B

TFP Expert
LifeTime Supporter
Jun 7, 2011
15,006
Midland TX
Go ahead and put 5 drops of the color indicator in. It will not affect the results, and you can see the endpoint much better. You can confirm this by completing the test with the three drops as usual. After you do that, put a couple of more drops in to confirm what I said. If you are at endpoint, it will just be a darker blue. This is something we do in the water treatment world as S.O.P. on a daily basis, even for low level hardness testing. Please note that this is ONLY for the color indicator.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
I have a kit that is over 3 years old and all the reagents still seem fine as well.

Have you read the extended test instructions? Wondering if something there may jump out ... like you are seeing a fading end point or something.
extended-test-kit-directions-t25081.html#p206396

Are you using the Speedstir? If so, I would suggest NOT using the built in light.

Thanks for the info Brushup, I was thinking adding more of the color would not hurt, but was not sure.
 

HouTex

LifeTime Supporter
Mar 7, 2011
413
Houston, Texas
jblizzle said:
I have a kit that is over 3 years old and all the reagents still seem fine as well.

Have you read the extended test instructions? Wondering if something there may jump out ... like you are seeing a fading end point or something.
extended-test-kit-directions-t25081.html#p206396

Are you using the Speedstir? If so, I would suggest NOT using the built in light.

Thanks for the info Brushup, I was thinking adding more of the color would not hurt, but was not sure.

Don't use the light? Without the light it was even worse for me to see!

Yes, I read the extended instructions and tried those procedures as well. Same result.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
I think the light ends up washing out the light colors ... make it very hard to see the end point of the FAS-DPD tests. Just my opinion though.
 

Patrick_B

TFP Expert
LifeTime Supporter
Jun 7, 2011
15,006
Midland TX
You're welcome Jason, no sweat.

I want to second Jblizzle on not using the light. At least to start, and I strongly discourage it for new users. Reason being is that the light washes out the true endpoint colors. You can see them best with strong ambient light, particularly against a white background. In a lab setting, these types are run in a white ceramic dish, under bright light so you can see every subtle change. The speedstir light shining through the liquid actually distorts the color because it has a slight bluish/purple tinge to it. This is particularly distracting on blue-ish end points as with the CH test. I have run many thousands of TH and CH tests over the years, and I firmly believe this based on my experience. Learn how to really see and judge the endpoint before you use the light under the sample. The only time I use it is to run FC after dark. Otherwise it is just too distracting.
 
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