CH results vary between TF-100 and TF-Pro kits

[PatricksPool]

I've had the TF-100 since late January this year, but I also just picked up a TF-Pro this month. I'm currently bringing my CH up to ~350 from the low point of 200. Everything was going well until I used the TF-Pro to test today, then I compared results between the two.

3/31: I started with CH 200 on 3/31, adding 8lbs calcium chloride and that brought me up to 250
4/12: I got 275 CH on another test 4/12 without adding any, that may have been my interpretation of the color change that day
4/14: 250 CH and added 8lbs calcium chloride
4/15: 300 CH
4/16: 8lbs calcium chloride
4/17: 325 CH
4/19 12PM: 325 CH, then 8lbs calcium chloride.

This all made sense from what I was seeing in PoolMath effects of adding, but today I switched over to the TF-Pro and got conflicting tests...
4/19 10PM *TF-100* CH 375 (15 drops) // *TF-Pro* CH 550 (22 drops).

I did them side by side to reduce the chances of interpretation. My testing thus far has been pretty predictable.

I've got my PoolMath logs posted but I haven't entered any data in for todays CH post addition since I got conflicting results between the two kits.

 

[BenB]

Very interesting. Somebody posted a similar story recently, it turned out the new bottle had a small blockage in the tip causing different drop sizes. Have you checked that the bottles are both clear and unobstructed?

Clearly given the age of both kits, you are right to expect no difference between them.

 

[revitup]

Can you swap tips between the bottles?

 

[mknauss]

Please report your issue to [email protected]

 

[sacredcow]

Can you swap tips between the bottles?

I had this issue when replacing a kit last year. Across the board, EVERYTHING drop-based was WAY higher, as in more than double. It appeared to me that the drops were falling off the tips of the new reagents smaller so I swapped them out with the tips from my old set and everything went back to normal. My theory is that there was a release agent from the molding process still on the tips and breaking the surface tension, because the size of the orifice shouldn't matter. A good cleaning with an alcohol wipe might have accomplished the same thing.

 

[BenB]

Definitely worth reporting. We (users of the site) put a huge amount of trust in the TF kits producing accurate, repeatable results and actively recommend it to new users. We should be able to trust that they are doing sufficient QC on their end to make sure that's the case.

 

[PatricksPool]

Thanks for all the feedback. There is no obvious blockage in the tips. I've reached out to TFTestKits. I'm going to do a full comparison to see what else might be amiss. For now I'm not trusting any tests out of the TF-Pro.

 

[OTPirate]

The chemistry is all the same and Taylor Technologies has had no reports of any issues with their reagents. I will email them just to double check. Are you using the Smart stir with both tests? A magnetic stirrer does seem to help with CH testing.

 

[wireform]

Two weeks back I swapped all the regents out for a newer set from last season with my TF100. Just last Friday I was doing testing with the new set of regents and was having a very difficult time with R-0011L regent. Not only wasn't it falling off the tip but I was squeezing the bottle and still barely got anything let alone an unreliable droplet size. So I popped off the tip, used my air compressor rinsed it with hot water and again blew it out only for there to be no difference at all. Still can't get a drop out without pressure. I removed it again this time inspecting it with my BAUSH & LOMB 5X loop from the inside only to realize how these tips actually work. The inside of the tip has a plastic partition which has a tiny hole for the regent to pass through. A trick I use when overhauling carburetors on outdoor equipment I use ONE copper strand of wire from 14awg stranded wire to clean the micro orifices. I used one and pushed it through several times and the rest is history. Now it works as it supposed to.

 

[PatricksPool]

Just a quick update. OTPirate is sending me a CH Standard solution to conduct further testing with. I did side-by-side tests tonight with both kits. Everything is in sync except for the CH, which is good news.

TF-Pro had CH 550 while the TF-100 was at 375 -- at least it's consistent, right!?

I re-did the TF-Pro CH again, but this time using the R-0012 from the TF-100 kit. I got 350, ehhh 375. It was my 4th time doing CH so the one drop difference didn't surprise me. This is after all the most subtle color change in my opinion.

So now I think I've narrowed the issue down to the R-0012 in the TF-Pro. So I swapped the tips, flushed the fluid in the tip by dropping 5 drops and repeated the test. Was still getting a CH of 550.

One more test: Using the TF-100 R-0010, R-0011L and using the TF-Pro R-0012, I got 550ppm.

So, definitely looking like the TF-Pro R-0012 is the culprit.

 

[jamesey]

I just purchased the TF100 XL a couple weeks ago and it came with a defective R-0012 tip. My issue was that the reagent was shooting out small droplets rapidly instead of forming a single droplet like the others.

Rebecca @ TFTestKits fixed the issue right away. Great customer service!!

 

[wjmano]

I too had concerns with my CH results when using a brand new TF-Pro kit. I contacted TFTestKits yesterday and thought I'd pass along the response I received from Rebecca...

"...the issue is the static electromagnetic effect that can develop on the R-0012. Try this-wipe the tip of the R-0012 with a damp paper towel between each drop. When 12 is fresh it will get so eager to jump in the solution it will not form a full drop, thus skewing your results. It will go away soon."

I'll give it some time for my R-0012 to age and wipe down the tip as suggested, but I also wonder why changing out tips worked for some.

 

[wireform]

I've never had it with the CH but is common on the TA (R-0008) regent. After some time it starts to behave....

 

[gigi747]

This thread has helped me out!

After being MIA for a while, I'm back in the pool game and decided to order the new TF-Pro kit to compliment my new pool.

My Pool Builder is doing the first month of start up and all my test results line up with his, except for my CH levels which are almost double. The CH reading from my local pool store led me to believe that my test was most likely the one that was off:
Builder: 251 ppm
Pool store: 198 ppm
me: ~450 ppm

Here are my TF-Pro CH readings since I first started testing, note the trend lower.
5/29 - 450
5/31 - 475
6/1 - 450
6/2 - 400

My Hach 5B gave me a reading of about 342 ppm. Yes, it's probably not the most accurate test, but I had it and it gave me another data point to think about.

Today I was getting "fading endpoint" in my test so I added 5 drops R-0012 before the others. This still gave me a CH reading of 400. Next I redid the test with 50/50 pool water and distilled water but wound up with 400 ppm again. Next, I found this thread and ran a piece of wire through the tip of my R-0012 bottle. Next I redid my CH test but used 8 drops(it seems the # of drops of R-0011L is not critical?) of R-0011L instead of 3. This gave me a reading of 250 ppm, and gave a nice shift straight to blue instead of purple. Next I redid the CH test, but used a 50/50 mix of pool water and distilled water which resulted in a reading of 250 ppm. Lastly, I redid the test normally and achieved a result of 225 ppm.

My takeaways:
*Use more indicator than the suggested 3 drops. (anyone care to comment on effects of using more than the suggested 3 drops?)
*Using a 50/50 solution of pool/distilled water cuts down on the amount of my suspended magnesium.
*Straight out of the box my TF-Pro CH test was inaccurate, but its results appeared to be trending lower over time.
*The copper wire trick worked, whether it cleaned the orifice or changed the charge of the tip, I do not know. (Irradiated mail?)

I guess I'll see how my following CH results end up, but it appears that I am now getting the results that I should.

Thanks TFP