TF test kit gone crazy??

[sbalberti]

I've been using the TF 100 kit for my new pool since June of last year. The reagents I've been using were purchased about 9-10 months ago. I ordered a new refill kit about a month or so ago and just now have started using them as the last set started running out. My CL, TA tested right in my normal ranges that they've been the last 9-10 months. The CH test on the other hand, jumped from 275 from last week (old reagents) to 425 this week (new reagents). In the last week I've only added 10% liquid chlorine and we've had one rain shower. I repeated the test multiple times and then tested my tap water which was 75. One thing I noticed when I turn my speed stir off is little blobs of purple color floating in the water which i don't recall seeing with my last set of R0010,11 and 12 reagents. Am I going crazy or do I have a bad set of reagents?

 

[JamesW]

Calcium Hardness Test Interference - YouTube

 

[JoyfulNoise]

Also, be sure that you are counting drops correctly and that you are actually getting to the end point. The test ends when the sample water reaches it's deepest blue color NOT when the color transitions from red/purple to blue.

 

[JamesW]

Compare the drop size of both reagents to see if they are the same. Sometimes you need to wipe the tip to keep it dry and static free.

 

[sbalberti]

Compare the drop size of both reagents to see if they are the same. Sometimes you need to wipe the tip to keep it dry and static free.

I've already thrown the old reagents away. I use a speed stir with the light and always meticulously clean my tubes. I've been getting steady results for 10 months with no crazy results until today. No scaling at the water line either. I thought you only had to worry about static and wiping the tip on the TA test?

 

[JamesW]

Sometimes the tip gets wet and the drops come out too big.

Sometimes static can build up and make the drops the wrong size.

Try wiping the tip and do the modified procedure as shown in the video.