TF-100 vs Taylor K-2006 Total Alkalinity Discrepancy

[npawelek]

I recently purchased a TF-100 to replace my Taylor kit and update reagents as some were aging. With the kit I also purchased the case and a pack of standard samplers for validation purposes.

When testing TA using the standard solution, the TF-100 was reading TA at 80 instead of 100. I was doing 25ml of the standard in the graduated cylinder while using the speed stir, 2 drops R-0007, 5 drops R-0008, and then counted 8 drops before the color changed from green to a bright red. The first time I thought I messed something up, which is why I ran it again and was surprised to see the same result. I didn’t have enough for a 3rd 25ml test, so I used the 10ml and used my Taylor TA reagents instead (expiration 7/24 and 11/24). It read the 10ml as 100ppm, as I’d expect.

When testing my pool water, I notice the same level of inconsistency, the TF-100 gives me a TA of 60 and the Taylor 70.

Has anyone experienced this before? Makes me wonder if I made a mistake switching to the TF-100 kit.

 

[Newdude]

Most Taylor tests are accurate to 1 drop. In this case, if your TA was actually a 90, both 80 and 100 are acceptable.

For funsies, swap the tips and see if the results change.

Also, be sure to wipe the tip of the bottle between drops. That one gets static charged in shipping and may be screwy the first few tests. Its usually high, but I wouldn't bet a paycheck on it either way.

I find some of the bottles I rarely use are very stiff and the drops seem to be smaller. Maybe the new bottles will break in after a few tests, helping further.

At the end of the day, none of it matters if you're +/- 10. We need to be that close, but don't need to be dead on. We know it's not a 150, nor a 50.

 

[npawelek]

Calcium hardness seems to be off by a bit more. There is a difference of 50ppm between reagents. On the R-0012, its 100% the stiff bottle which seems to result in larger drops. Tips are not interchangeable between the kits either. The TF-100 has a larger opening on the bottle side.

From a water balance perspective, it seems like the variability can lead to a much different test result in the end.

 

[Newdude]

From a water balance perspective, it seems like the variability can lead to a much different test result in the end.

It would be. And they are the same reagents so there should be no considerable variances. How old are the old ones ? They're likely not reading well anymore. Where do you store them ? I have my kit climate controlled on the shelf in the coat closet. Do you guys have shorts closets in TX ? What goes in your coat closet ?

Calcium hardness seems to be off by a bit more. There is a difference of 50ppm between reagents.

Welp. That's +/- one drop @ 25 per drop. For example, actual 300 may test 275 or 325. So it's still within reason, and just like the TA, won't change the price of beer. We need to know you have 300 ish and not 75 and not 1000.

 

[proavia]

Keep adding drops until the color doesn't change.
Subtract the last drop that does NOT change the color.

 

[npawelek]

How old are the old ones ? They're likely not reading well anymore.

They expire in December this year. Since they’re the same reagents I intermixed testing across kits. Results are the same, so I think its a combination of the stiff bottle and tip on the R-0012. The drops look larger and come out slower on the TF-100 kit. My only other option would be to switch bottles entirely… I feel like this kinda defeats the purpose.

Where do you store them ?

Inside a closed kitchen cabinet, outside of direct sunlight.

 

[npawelek]

Keep adding drops until the color doesn't change.
Subtract the last drop that does NOT change the color.

Yep. This is precisely how I’ve been testing.

 

[Sarah and Nate]

The material or rigidity of the bottle does not affect the drop size. The size and construction of the dropper tip affects the drop size. That said, some incorrect tips have worked their way into our inventory as of late and thus this is likely attributable to that. I've responded via email to the original poster already, but if others find this thread after the fact please reach out to me at [email protected]
Nate

 

[npawelek]

The material or rigidity of the bottle does not affect the drop size. The size and construction of the dropper tip affects the drop size. That said, some incorrect tips have worked their way into our inventory as of late and thus this is likely attributable to that. I've responded via email to the original poster already, but if others find this thread after the fact please reach out to me at [email protected]
Nate

Thank you!

 

[mgtfp]

To verify if it's the dropper, you can refill the Taylor bottle with the TF100 reagent.

 

[mgtfp]

Just saw that Newdude already came up with that suggestion. Clever guy.

 

[npawelek]

The material or rigidity of the bottle does not affect the drop size. The size and construction of the dropper tip affects the drop size. That said, some incorrect tips have worked their way into our inventory as of late and thus this is likely attributable to that. I've responded via email to the original poster already, but if others find this thread after the fact please reach out to me at [email protected]
Nate

The new tips solved the issue. Thank you again!

 

[PoolStored]

The new tips solved the issue.

Nope, dog still looks the same...