Accuracy of TFTkits Vials May be in Question...

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GoGrabTheNet

GoGrabTheNet

0
Dec 13, 2015
81
Surprise, AZ
In comparison to the Taylor vial that comes with the Speed Stir, it seems that the vials that came with the TF-100 test kit (i.e. the blank vial and also the "Chlorine" vial) may be inaccurate. I filled a 10ml graduated cylinder with water for the test and emptied it into the TFTkit vial(s). Each one had the water line well below the 10mL line, meaning the top of the meniscus (albeit very hard to detect) was below the line. Refilling the graduated cylinder again to the 10mL mark and then pouring it into the Taylor vial put the bottom of the meniscus right on the 10mL mark. Furthermore, to flip the test around, I filled the TFTkit vial to the 10mL mark and poured its contents into the dry Taylor vial. The water went to the 11.5mL mark.

So what does this mean?

Well, if you're always filling the TFTkit vials to the same mark every time for every test, then there really isn't an issue as one test is relative to the next. However, the value of the FAS/DPD drop test, or other tests for that matter, may be inaccurate. For example, I performed two FAS/DPD tests, with one having exactly 10mL from the graduated cylinder and the other having the water-line/meniscus right on the vial's 10mL mark. The results were 33 drops vs. 37 drops, respectively. That's a difference of 2 PPM--pretty significant, no? Furthermore, one gave a drop's worth of CC's (the exact 10mL test) while the other did not.

Anyone else notice this?

Now...my graduated cylinder could be off, but not likely. It is a cheaper plastic one as opposed to a Pyrex piece. Despite this, it's still probably more accurate than the eyeball-looking-straight-on-the-vial technique. The plastic graduated cylinder gives that nice, "scientific" meniscus, as it should be. Overall, the meniscus was very pronounced in the graduated cylinder, and I would have no problem putting my confidence into the reading of "10mL."

Knowing this, I believe I may now get more accuracy with the CYA test. Now I can effectively measure out 15mL of water and R-013 rather than eyeball the vials.

Splitting hairs perhaps, but I thought I'd mention my findings.
 
GoGrabTheNet said:
In comparison to the Taylor vial that comes with the Speed Stir, it seems that the vials that came with the TF-100 test kit (i.e. the blank vial and also the "Chlorine" vial) may be inaccurate. I filled a 10ml graduated cylinder with water for the test and emptied it into the TFTkit vial(s). Each one had the water line well below the 10mL line, meaning the top of the meniscus (albeit very hard to detect) was below the line. Refilling the graduated cylinder again to the 10mL mark and then pouring it into the Taylor vial put the bottom of the meniscus right on the 10mL mark. Furthermore, to flip the test around, I filled the TFTkit vial to the 10mL mark and poured its contents into the dry Taylor vial. The water went to the 11.5mL mark.

So what does this mean?

Well, if you're always filling the TFTkit vials to the same mark every time for every test, then there really isn't an issue as one test is relative to the next. However, the value of the FAS/DPD drop test, or other tests for that matter, may be inaccurate. For example, I performed two FAS/DPD tests, with one having exactly 10mL from the graduated cylinder and the other having the water-line/meniscus right on the vial's 10mL mark. The results were 33 drops vs. 37 drops, respectively. That's a difference of 2 PPM--pretty significant, no? Furthermore, one gave a drop's worth of CC's (the exact 10mL test) while the other did not.

Anyone else notice this?

Now...my graduated cylinder could be off, but not likely. It is a cheaper plastic one as opposed to a Pyrex piece. Despite this, it's still probably more accurate than the eyeball-looking-straight-on-the-vial technique. The plastic graduated cylinder gives that nice, "scientific" meniscus, as it should be. Overall, the meniscus was very pronounced in the graduated cylinder, and I would have no problem putting my confidence into the reading of "10mL."

Knowing this, I believe I may now get more accuracy with the CYA test. Now I can effectively measure out 15mL of water and R-013 rather than eyeball the vials.

Splitting hairs perhaps, but I thought I'd mention my findings.
Click to expand...
I noticed the same thing. The vial in the speed stir is quite a bit off from my kit. You are not alone. I need to do more work to determine which one is wrong.
 
I just filled a Nipro syringe to 10ML and put it in both tubes and this is my result. These are what we use to administer medications at the hospital so I have to believe they are pretty accurate.

Chlorine - 11.5
Plain - 11.25

- - - Updated - - -

So do we compensate and fill the TF-100 to 11.5 or are the tests made for those tubes? Has anyone tried running tests at 10ml and 11.5ml to see how much difference it makes?
 
I have replaced all my vials with Taylor vials and use the SampleSizer for repeatability. The bottom of the miniscus is at the 10 mL or 25 mL line when I use the SampleSizer slow and easy. It speeds up all my tests since I can quickly assess whether the miniscus is where it should be without having to add slowly from a pouring container or dropper.

TFTestkits.net
TFTestkits.net
 
Akathisia said:
I have replaced all my vials with Taylor vials and use the SampleSizer for repeatability. The bottom of the miniscus is at the 10 mL or 25 mL line when I use the SampleSizer slow and easy. It speeds up all my tests since I can quickly assess whether the miniscus is where it should be without having to add slowly from a pouring container or dropper.

TFTestkits.net
TFTestkits.net
Click to expand...

I also use this and it works exactly the same every single time...
 
Oh no, this could mean the pool store was correct! My " other" vial is and I purchased my test kit 10 years ago. I just use my Taylor vial.
 
OTPirate said:
Morning! The TFTestkit cylinders have been recently been tested and proven to be accurate. Please contact me at [email protected] if you are having any issues and I'll be glad to look into it. The TFTestkits cylinder do not work with the Samplesizer.
Click to expand...

Thanks for the response. I bought my TF-100 kit near the end of August 2015. Has it been updated since then? I do indeed like the TFTkit vials for their clarity. I can still use them for my tests, but will start accurately measuring solutions using the grad cylinder.

BBailey said:
Oh no, this could mean the pool store was correct! My " other" vial is and I purchased my test kit 10 years ago. I just use my Taylor vial.
Click to expand...

LOL! Pool store still wants you to buy more shock! :)
 

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OTPirate said:
The TFTestkit cylinders were upgraded about a year ago to have 1 ml line gradations apart for easier reading. The cylinders are designed to measure the same as Taylor Technologies cylinder (9198) as TFTestkits only uses Taylor reagents. They are not designed to be measured against medical instrumentation. TFTestkits cylinder - YouTube
Click to expand...

Thanks for the information. My recently ordered kit has the older cylinder (no 1 ml line graduation). 10ml in the TFTestkit cylinder is approximately 11.5ml in the Taylor cylinder. Reading between the lines, I imagine the new cylinder matches the Taylor cylinder. I will toss the TFTestkit cylinder and use the Taylor. I appreciate your help.
 
I noticed the graduated cylinders in my TF-100 kit didn't agree with each other but who expects great accuracy from cheap plastic cylinders? I fill from a syringe that I know is more than accurate for what I'm doing and ignore the marks printed on the cylinders. With the syringe I get excellent repeatability (with reasonable accuracy) and that's all I'm after.
 
I have a question -

Assuming that we are using Taylor reagents, are the test results accurate using exactly 10 ml water sample or are they accurate using the marks on the Taylor vial? Taylor may have calibrated their chemicals in their lab to give accurate results using the volume marks in their vials.

Mike.

- - - Updated - - -

OTPirate said:
The TFTestkit cylinders were upgraded about a year ago to have 1 ml line gradations apart for easier reading. The cylinders are designed to measure the same as Taylor Technologies cylinder (9198) as TFTestkits only uses Taylor reagents. They are not designed to be measured against medical instrumentation. TFTestkits cylinder - YouTube
Click to expand...

So you used the Taylor vial as your standard but what did Taylor use as a standard when they developed their test chemicals?

Mike.
 
This subject has been hashed over and over for the last 8 years. Repeatability and dependability are both more important to the tests we perform.

So, let's say you measure 5.0 ppm chlorine in your pool but you send the same sample off to a science lab and they get 6.0 ppm. So what?

The difference between managing your pool at 5 or 6 ppm is inconsequential. What is important is repeatability......your ability to bring tomorrow's results back up to 5 ppm again.....day after day.

The TF-100 does that just fine and is being used, without issue, in thousands and thousands of pools across the US.

I am sure a test kit can be put together that measures what we do with more scientific precision.......how much would we be willing to pay?

A driving tenant at TFTestkits has ALWAYS been to keep the TF-100 at a price that makes it affordable to most everyone, yet produces all the test results you need to have a crystal clear pool. The TF-100 does both those things very nicely.
 
duraleigh said:
This subject has been hashed over and over for the last 8 years. Repeatability and dependability are both more important to the tests we perform.

So, let's say you measure 5.0 ppm chlorine in your pool but you send the same sample off to a science lab and they get 6.0 ppm. So what?

The difference between managing your pool at 5 or 6 ppm is inconsequential. What is important is repeatability......your ability to bring tomorrow's results back up to 5 ppm again.....day after day.

The TF-100 does that just fine and is being used, without issue, in thousands and thousands of pools across the US.

I am sure a test kit can be put together that measures what we do with more scientific precision.......how much would we be willing to pay?

A driving tenant at TFTestkits has ALWAYS been to keep the TF-100 at a price that makes it affordable to most everyone, yet produces all the test results you need to have a crystal clear pool. The TF-100 does both those things very nicely.
Click to expand...

I believe that the vial can be manufactured with the measure marks placed accurately for the same price as not accurate. the marks are set once and the manufacturing process repeats that mark in the same place for each and every vial that it spits out. Medical syringes can be bought for a couple of bucks each.

I've been measuring my water samples with a veterinary syringe simply because it is very easy to measure quickly and just squirt into the vial and I know that the sample is always consistent.

Mike.
 
I assure you my eyes are off more than ANY 10ml sample size on the planet! Throw in a little glare to go with it, and.............you see. And if I'm down to worrying about that possible last difference of .2 or .5 ppm of FC on a daily basis keeping my pool clear, I obviously don't "know" my pool after 8 years.
 
The OP is talking about a 2ppm discrepancy measuring chlorine and that is significant to me. I agree that consistency is more important to me than accuracy but if I want +-1ppm accuracy I can use paper test strips which are cheaper and easier to use than a liquid test. Accuracy is the reason that I'm willing to spend more time and money on a water test kit.

Until i hear differently I'll use a syringe to measure the sample assuming that Taylor is calibrated to a 10ml sample and that their plastic vial is just not made accurately.

Mike.
 
OTPirate said:
The TFTestkit cylinders were upgraded about a year ago to have 1 ml line gradations apart for easier reading. The cylinders are designed to measure the same as Taylor Technologies cylinder (9198) as TFTestkits only uses Taylor reagents. They are not designed to be measured against medical instrumentation. TFTestkits cylinder - YouTube
Click to expand...

So it doesn't matter if the cylinders are not matching other equipment because they were made specifically to be used with the regents in the test kit? So, as long as we follow the test kit instructions and use those cylinders included in the kit we are getting accurate results? Don't compensate for the difference?
 

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