Can Leslie's be so wrong with their water testing?

neuronpool

LifeTime Supporter
Jun 8, 2012
13
Long Island, NY
#1
Hello all,

I wanted to share my experience with the TF100 test kit that I just purchased.

I did all the testing according to the directions on the laminated sheet included in the kit. My results were similar to a recent local Leslie's testing except for two.

My TA 190 and CH 300
Leslie's TA 90 and CH 240

I got to think how could it be so different?

I got this kit as it seemed like a general consensus in this forum that Leslie's testing cannot be fully trusted. I could imagine this to be true as Leslie's modus operandi is to make money by selling pool chemicals. But I would think they cannot willfully or unknowingly be testing that is way off. The plausible explanations of my test numbers being different from Leslie's were;
1. the TF test kit is no good.
2. Leslie's testing is no good.
3. I am not doing the test properly

I repeated the TA testing two more times and got 210 and 190(average of 200). As the three numbers were very similar, I had ruled out number 3. I was not so concerned about CH at this time as it was within normal range.

I brought a water sample to the same Leslie's for repeat testing which showed TA 100 and CH 220. I noticed that Leslie's uses a electric stirrer while doing TA testing. hmmm, i thought. While talking to one of the workers, I was told that the testing droppers should be held 90 degree vertically as opposed to holding it obliquely (as I was doing) to obtain more consistent drop volume. hmmm.

I got back home and re-did the TA testing (three times) while vigorously agitating the testing tube with each drop of the reagents off the bottles in a vertical fashion. I could not believe the difference it made. More I agitated the test tube, the lower the TA reading. The numbers were 170, 150 and 110. The last one with almost constant agitation to emulate the electric stirrer. I even wet-wiped the tip of the reagent as per the direction this time (something about static).

It turns out that my 110 is not "too much off" from 90 - 100 that Leslie's was getting (I am assuming that the lowest number is the most accurate).

I would think that CH testing may also be affected quite a bit by the agitation of the test tube. I will repeat it soon.

I think it is important for people to know that to get an accurate TA reading, the technique is important as wrong test numbers may lead to unnecessary acids being poured into the pools. High TA seems to be a common issue in this forum.
 

harleysilo

TFP Expert
LifeTime Supporter
Mar 1, 2012
1,924
North Georgia
#2
hmmm I have the test kit and the speed stir, i'll try a speed stir vs. hand swirl TA test tonight. I've always used the speed stir, and have not hand swirled.....however it your experience and mine shows to me how important the stirring is then I'm going to start thinking about timed stirs......
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
#3
The speed stir can make a significant difference on the CH test, but should not affect the TA result.

The TF-100 is one of the top test kits out there, no possible problem there.

Pool stores in general have an amazingly bad record for getting test results right, even when using good quality test kits.

While it is quite possible for you to do a test wrong, that isn't all that common.

It is important to hold the dropper bottle vertically with the tip pointing straight down.

The sample should be swirled around continuously, either by hand or with a stirrer.

On the TA test it is a good idea to wipe the tip of the dropper bottle with a damp cloth or tissue every few drops.
 

CaOCl2

LifeTime Supporter
May 23, 2007
326
Montreal Canada
#4
With any stirrer, add a drop and wait for the reaction to complete (or for the endpoint to appear) before adding another drop, sometimes it may take a second or so to get a change of color. I've seen this very often in the CH test.

There's a study out there (Ansermot, Griffiths, Bonnabry from the Geneva University Hospitals Pharmacy) that actually studied the reliability and reproducibility of dropper bottles and delivered volume per drop. They found that bottle inclination had the biggest influence on delivered drop size. In 12 cases out of 16, a 30 degree inclination of the bottle yielded a volume between - 12% and + 12% of the manufacturer's specs. Their main recommendation is to hold the bottle vertically when dispensing.
 

Mike_k

Gold Supporter
LifeTime Supporter
Apr 16, 2012
119
Mason, Ohio
#5
With your varying results it might be a good idea to get a bottle of TA Standard Solution from TFTestKits.
You perform the TA test exactly like you would normally but substitute this solution instead of pool water. Results should yield a TA of 100ppm

This is an inexpensive way to test the validity of your TA chemistry as well as to verify your testing methods
(and you could order the SpeedStir at the same time)
 

RobbieH

TFP Expert
LifeTime Supporter
Aug 30, 2010
4,052
Dallas, TX
#8
Keep in mind who's doing your testing at Leslie's. The Leslie's by me typically has a teenager behind the counter, and one that I am almost certain has not been studying chemistry in high school. And I usually see her use some sort of strip test and an electronic reader, not drop tests. If someone gave her drop tests, I'm betting her results would be equally as bad anyway. She has also admitted to me she has never owned a pool.