I say 220 he say 140 how can that be?

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engrav

engrav

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Jul 4, 2012
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Whidbey Island, WA
Recently had a pool company out to discuss resurfacing and he offered water testing, I said sure
Everything was close to my K2005 reads save CH
I say 220 he say 140
testing person in their store is not a newbie nor a dummy; been around the water testing block many times
how can it be that all tests were close save CH and it is off a long way
thank you
 
We don't usually spend too much time worrying about why pool store testing doesn't match because they are usually inaccurate. There are many, many reasons why and, the fact is, you are the best source of your own water testing because you have the best test kit on the market. Chances are the pool company is using a digital/electronic tester which can be off or he's testing methodology is flawed. Either way, it doesn't really matter because you have the best kit on the market for testing and you care the most about getting the right results...the pool service guy is just there to make money off you.
 
JoyfulNoise said:
We don't usually spend too much time worrying about why pool store testing doesn't match because they are usually inaccurate. There are many, many reasons why and, the fact is, you are the best source of your own water testing because you have the best test kit on the market. Chances are the pool company is using a digital/electronic tester which can be off or he's testing methodology is flawed. Either way, it doesn't really matter because you have the best kit on the market for testing and you care the most about getting the right results...the pool service guy is just there to make money off you.
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But he matched everything else and
he is a good guy with lots of experience
so I wonder if there is a valid reason
( I suppose could be simple error )
 
What test is he using, do you know?


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006
 
His regents are older than your? His regents have been out in the sun? His regents got over heated? Pick one any one or even two.

Trust YOUR tests and know you are doing a good job taking care of your pool

Kim
 
Just as a general matter, the Taylor CH test is probably one of the hardest to perform. Not only are there chemical interferences that can make the color transition difficult to detect but there are also people who just genuinely have a hard time seeing the endpoint go from the pinkish-lavendar color to the light blue color. I find it difficult to do so I only do the test outdoors when there's good sunlight and I use a sheet of white paper behind the test vial to help make the colors standout better. Even with all that, it's easy for me to miss the color transition.

Most test shops do these tests under very poor lighting conditions or on light tables that don't render the colors well. They also tend to do many of these tests all in a row and so sloppiness can be a big issue. I'm not trying to immune the character of the fellow doing the test, but the fact is, you care more about getting the right result than he does. The only way to truly know for sure if you are both doing the test correctly is for you to both perform the test using the SAME tester. In other words, you both need to go to the pool with a freshly purchased K-2006 and you both need to perform the test using the same reagents, the same sample bottle and test protocol. That is the only way to detect operator error. Different test kits (like a K-2006 versus a LaMotte ColorQ) will almost always give results that are different, particularly in the CH test because that particular analytical chemistry method is very sensitive to both the person doing the test and the protocol and chemicals used in the test.
 
Did you watch him perform the test? In my somewhat limited experience I find that pool stores and pool professionals in general rush the tests. Just watch a few YouTube videos.

They are putting in drops at a rate that resembles a steady stream. I was rather surprised the first time I saw this but it seems to be consistent in my experience. The greater the percentage of chlorine in the blood the more they rush through the tests and the less their count seems to resemble the actual number of drops.

Pool services have to get to all the pools on the route that day. Pool stores have the line of customers behind you. They have an incentive to move quickly. I prefer slow and deliberate.
 

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well
I emailed and asked how he did the test and why he thinks so different (when all other tests were dead on)
will wait and see if he responds
I could buy some strips and see if result closer to his or mine I suppose
or just forget it but
is a puzzle
 
engrav said:
well
I emailed and asked how he did the test and why he thinks so different (when all other tests were dead on)
will wait and see if he responds
I could buy some strips and see if result closer to his or mine I suppose
or just forget it but
is a puzzle
Click to expand...
Forget the test strips, oh I mean "Guess Strips" - they are junk.

People who have been "around the block" tend to try to go fast, cut corners and make educated guesses. I've watched the store manager who I know understands testing squeeze the reagent bottle so hard that it looks like a stream rather than well formed drops.

The pool owner take their time, reads the instructions because they are a little unsure, and do better testing as a result.
 
tim5055 said:
People who have been "around the block" tend to try to go fast, cut corners and make educated guesses. I've watched the store manager who I know understands testing squeeze the reagent bottle so hard that it looks like a stream rather than well formed drops.
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Tim is 110% correct. If you read up on dropper tips, you will find that they meter "X" amount at a speed of around 1 drop per second. The drop must have time to accumulate the required mass on the tip, before gravity takes it away. Any "squirtishness" defeats the physical mechanics of metering.
 
ewkearns said:
Tim is 110% correct. If you read up on dropper tips, you will find that they meter "X" amount at a speed of around 1 drop per second. The drop must have time to accumulate the required mass on the tip, before gravity takes it away. Any "squirtishness" defeats the physical mechanics of metering.
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got it, thank you
still awaiting his email response
 
here is his reply
==============

I use the same test kit as Taylor is the best on the market.*

If you buy from us you usually get about 2 years of use as we get to buy direct from the manufacturer.* If you buy from another company or on line it is recommended to replace all reagents each spring as they come from a distributer that makes a bulk purchase each year to get a discount and you have no idea how old they are.* The newer ones finally have an expiration date on them and if you keep them from getting too hot or cold they can exceed that date.*

I test the accuracy of pH, total alkalinity, calcium hardness and cyanuric acid for my lab with standards to make sure they are accurate.* Once the reagents get too old or have gone through extreme temperatures in either direction they will go bad before the expiration date.* Also, if you leave your kit in someplace cold the dropper shrinks to give you a higher reading as the drops are smaller and if left somewhere hot they will expand and give you a lower reading based on drop size.* Ours are kept at room temp for the lab and the new stock is kept in a cool warehouse before use so they don’t exceed temp range.*

Our pool cleaners must bring their test kits in from their trucks each day during the summer and winter to prevent them from getting false readings.* Also, if you squeeze the bottles too firmly to take the test you will get smaller drops therefore getting a higher reading.* The calcium test is more susceptible for this than the total alkalinity test due to the makeup of the reagents.* I have learned this from testing myself.* It is very common that when one of our employee’s bring a sample from the field and they also tested it themselves that we get a different reading as they usually do the test quickly and the drops break off too early.* To have a 40ppm difference is common due to water level in the test vial, size of drops, how we view color change, not stopping with the drops while swirling as sometimes the drops need to mix, tainted or old reagents and that the calcium level isn’t the same throughout the pool.*

When I ran the resort chain and I trained multiple employees I made them all go to different areas of the pool for testing and the usual minimum and maximum levels of the 4 tests were 40-50ppm.* It also makes a difference if the pump has been off for awhile as the calcium starts to sink in stagnant water so you will get lower readings until the pump has been running at least 4 hours, less if the pool is brushed or vacuumed.
 
His last point about calcium "sinking" in stagnant water is, to say it nicely, HORSE PUCKY!

See this thread - Cyanuric Acid Location: Top, Bottom, or Everywhere?

Other than that, nothing he said surprises me. I still would trust yourself to do the tests right. If the pool guy uses Taylor, great for him. But his testing is subject to many more errors than your testing as he employs many different people to do the tests. Think about this way - there are both subjective errors (color rendering) and objective errors (droplet size, reagent temperature, etc) involved in testing. Therefore, two people doing the test with the same exact reagents can still get an error between them. However, your error and his error will always be the same for each of you respectively. In other words, your testing bias will always be the same for YOU. Therefore, you are the best person to do the test.

And let's be realistic for a minute. At the end of the day, the calcium hardness value for pools has a fairly wide range and can swing pretty far in either direction without ANY detriment to your pool. In fact, if you test weekly as is recommended, then you will always be able to carefully and diligently handle any CH problems that arise because it is a water parameter that changes VERY SLOWLY. So even if your testing is fairly far off, your pool will be ok.

I think this horse has been beaten to death, blended into a smoothie and fully digested. There's really not much more to say except, trust yourself and your own testing and save your money on an unnecessary pool service contract so you can buy more stuff for your pool.
 
trust yourself and your own testing and save your money on an unnecessary pool service contract
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Thank you

I have no contract. This was a simple grab, one-off thing while they were out to estimate resurfacing.

And
I will get some new reagents, I might be kinda out of date. And the bottles are sorta empty anyway.

Thank you.

one last query please
is calcium hardness a measure of calcium carbonate?
 
One thing to keep in mind in addition to rate that drops are formed, is also holding the dropper correctly (vertically) is very important, if it is at an angle it can greatly effect drop size causing your results to be off considerably.
 
One thing you can try doing is adding a few drops of the R-0012 EDTA titrant BEFORE you add any R-0010 calcium buffer. If you have any metal interferences, adding a few drops of the R-0012 will eliminate them. The only thing is you need to count those initial drops along with the later drops to get the total. Also, you can add an extra drop or two of the color indicator (R-0011L) if it helps you see the color differences better.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006
 

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