Local area pool store water testing descrepancies

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mijmic

mijmic

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Silver Supporter
Nov 22, 2014
41
Charlotte, NC
I usually bring a water sample to my local pool centers every couple of weeks or so, Leslie's and Oasis Pools in Charlotte. They're located approx. 2 miles from each other and more times than not, the reading printouts can vary significantly, as was the case today using identical samples taken from my pool at the same time and location in the pool.

My Leslie's reading today with their charted recommended ranges:


FAC (Free Available Chlorine) 4 (recommended range 1-4 ppm)
TAC (Total Available Chlorine) 4
Salt 2600 (rec. range 2500-3500 ppm)
Calcium Hardness (CH) 300 (rec. range 200-400 ppm)
Cyanuric Acid (CYA) 50 (rec. range 60-99 ppm)
Total Alkalinity (TA) 100 (rec. range 80-120 ppm)
PH (PH) 7.4 (rec. range 7.2-7.8)
Phosphates (Pho) 300 (rec. range 100 or lower)


My Oasis Pools reading today with their charted recommended ranges:

FAC 0.5 (rec. range 1-3 ppm)
TAC 3.0 (rec. range 1-3 ppm)
Salt 2800 (rec. range 3040-3520 ppm)
Calcium Hardness 280 (rec. range 200-450 ppm)
Cyanuric Acid 100 (rec. range 20-100 ppm)
Total Alkalinity 60 (rec. range 100-150 ppm)
PH 7.4 (rec. range 7.2-7.6)


As you can see, there's a big discrepancy in the respective FAC and CYA readings. The salt reading per my PDA was 3000. Oasis doesn't test for phosphates, and, from knowledge obtained from different sources, including this site, phosphate level isn't of much significance if the chlorine levels are sufficient and the water is clear. As I mentioned, the variance in the two pool stores is a usual thing, albeit the inconsistency is quite perplexing and frustrating. However, the discrepancy is usually in the not so critical category as the FAC. l

Since Oasis Pools was the later test, and where the low FAC reading resulted, I was strongly instructed to shock the pool. Since I hadn't shocked the pool most of the summer (thought there was no need to since the water has been clear all summer) and when testing with my Pentair Kit where you place 5 drops of applicable solution into particular vile section to check chlorine, PH, etc., the chlorine has generally tested dark yellow, so at least 3, I was a bit taken aback. Therefore, I purchased a case of their "Punch" and shocked the pool this evening. I added 6 lbs. of the recommended shock based on Oasis' advice. The Oasis person also told me that those kits that test for chlorine are deceiving as it doesn't test for FAC, but rather TAC. She advised that's why the water needs to be professionally tested for FAC!

As has been the case all summer, my pool water was crystal clear today...and at the time I added the shock this evening. Additionally, in the 2 years since my pool was built, I've never had any visible algae, and the water has always been clear to crystal clear.

I have the SWG set at 60%, which has been the norm during the summer months. My water temperature is currently 90 degrees...the pool is in full sun from mid to late morning until about 4 p.m.

Thanks for any replies!
 
And there is the problem-two "professional" pool stores tests that are SO far apart in what they found. :(

How much did this trip cost you? Now add in the cost the last time you went and what it will cost you the next time you go. For all of that together you can buy your own test kit and have rock solid test results.

What has happened is what we call "pool stored". They are there to sell you stuff. They did their job.

I strongly encourage you looking in my signature below for the test kit I think is the bang for the buck. This test kit can test your FC much higher and will be more accurate as well.

After you get your test kit share the results and we can help you get your water safe and balanced.

Until the test kit gets there have some reads here:

Pool School - ABCs of Pool Water Chemistry

This will tell the whys and hows of TFP.

:kim:
 
Hello:wave:

Kim is right.

It is very, very likely that you will spend less money and less time if you buy a kit and test yourself. Glad that your pool has been in good shape for the 2 years. The SWG is very likely the reason it has been so steady along with regular shocks. By the way the regular shocks are not required for a TFP pool and that alone will save you money.
 
We see a lot of inconsistent testing from stores.

Sounds like you are using a SWG and shocking as well. If you keep your FC/CYA ratio correct you wouldn't need to shock - but if you are happy with your current situation there is no need to change.

I 100% agree that doing your own testing is much more consistent.
 
mijmic said:
As you can see, there's a big discrepancy in the respective FAC and CYA readings. The salt reading per my PDA was 3000. Oasis doesn't test for phosphates, and, from knowledge obtained from different sources, including this site, phosphate level isn't of much significance if the chlorine levels are sufficient and the water is clear. As I mentioned, the variance in the two pool stores is a usual thing, albeit the inconsistency is quite perplexing and frustrating. However, the discrepancy is usually in the not so critical category as the FAC. l

Since Oasis Pools was the later test, and where the low FAC reading resulted, I was strongly instructed to shock the pool. Since I hadn't shocked the pool most of the summer (thought there was no need to since the water has been clear all summer) and when testing with my Pentair Kit where you place 5 drops of applicable solution into particular vile section to check chlorine, PH, etc., the chlorine has generally tested dark yellow, so at least 3, I was a bit taken aback. Therefore, I purchased a case of their "Punch" and shocked the pool this evening. I added 6 lbs. of the recommended shock based on Oasis' advice. The Oasis person also told me that those kits that test for chlorine are deceiving as it doesn't test for FAC, but rather TAC. She advised that's why the water needs to be professionally tested for FAC!

As has been the case all summer, my pool water was crystal clear today...and at the time I added the shock this evening. Additionally, in the 2 years since my pool was built, I've never had any visible algae, and the water has always been clear to crystal clear.

I have the SWG set at 60%, which has been the norm during the summer months. My water temperature is currently 90 degrees...the pool is in full sun from mid to late morning until about 4 p.m.

Thanks for any replies!
Click to expand...

This was very interesting to me. Leslie's tells you that your pool water is ok. Your own testing state you are ok. But in the end, you follow the advice of the one place that costs you money. LOL...

Kim is right. You have been "Pool Stored".

Definitely get yourself a good test kit and trust your testing. With the help of people from this board, you will keep your pool in pristine shape while keeping your money in your wallet where it belongs.
 

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needsajet said:
Almost everyone here has been in the same situation, so we like to have a chuckle about it :)

I hope you get a test kit and take control of your pool cause you'll never look back.
Click to expand...

Oh isn't that the truth! I have over $500 of chemicals that I bought before I learned about TFP. :mad:
 
I just wanted to chime in and say I ran a sample by the pool store today after testing to see how far off they were. Here are the results.

TF100:
  • FC 5.5
  • CC 0
  • TC 5.5
  • pH 7.6
  • TA 70
  • CH 200
  • CYA 80
  • Salt 2800

Pool Store:
  • FC 3.8
  • CC 0
  • TC 3.8
  • pH 7.1
  • TA 55
  • CH 100
  • CYA 50
  • Salt 3000

It amazes me that they didn't get a single value correct. I'm so glad I found TFP before I took possession of my pool. It's been a cake walk taking care of it so far.
 
_Eric_ said:
I just wanted to chime in and say I ran a sample by the pool store today after testing to see how far off they were. Here are the results.

TF100:
  • FC 5.5
  • CC 0
  • TC 5.5
  • pH 7.6
  • TA 70
  • CH 200
  • CYA 80
  • Salt 2800

Pool Store:
  • FC 3.8
  • CC 0
  • TC 3.8
  • pH 7.1
  • TA 55
  • CH 100
  • CYA 50
  • Salt 3000

It amazes me that they didn't get a single value correct. I'm so glad I found TFP before I took possession of my pool. It's been a cake walk taking care of it so far.
Click to expand...
Satisfying too right?!
 
I just bought the Taylor k-2006 and the results are different than Leslie's and i have been relying on them until now, now i am confused. I thought this kit was user friendly but i don't understand some things, maybe someone can explain them to me, here in the Pool School, it talks about FC and CC, now this kit, for chlorine, it has three bottles, one with DPD powder, what DPD stands for? , one FAS-DPD and DPD. I fill the container up to 25ml then i added a scoop of powder and it turned pink right away, then you use the FAS-DPD bottle and count the drops until it changes color, i think i went up to 20 drops and it still looked pink, so i stopped, what does this mean, am i producing a lot chlorine?. PH was about right 7.4, Calcium hardness i put 50 drops and it changed, does this mean 500?. Now this one is when i got really upset, Leslie's had told me that my CYA was at 60, with this kit, i follow the instructions and i start putting solution until the black dot disappears right? well i filled up the tube all the way and i still saw the black dot, meaning that i don't have any CYA right? and stupid leslie's made me buy a four pound of CYA powder. Thank you and i am sorry i don't understand much about these things. thank you.
 
Here is a link to the extended test directions that should answer most of your questions Pool School - Extended Test Kit Directions.

Short version, use a 10 ml pool sample for the FC/CC test, then each drop is 0.5. You might want to recheck CH using the above link. If you can see the dot you probably have low CYA. Hopefully it's a little fuzzy at least. If you are pretty sure you are testing according to the instructions, you will want to add a little.
 
nv269 said:
I just bought the Taylor k-2006 and the results are different than Leslie's and i have been relying on them until now, now i am confused. I thought this kit was user friendly but i don't understand some things, maybe someone can explain them to me, here in the Pool School, it talks about FC and CC, now this kit, for chlorine, it has three bottles, one with DPD powder, what DPD stands for? , one FAS-DPD and DPD. I fill the container up to 25ml then i added a scoop of powder and it turned pink right away, then you use the FAS-DPD bottle and count the drops until it changes color, i think i went up to 20 drops and it still looked pink, so i stopped, what does this mean, am i producing a lot chlorine?. PH was about right 7.4, Calcium hardness i put 50 drops and it changed, does this mean 500?. Now this one is when i got really upset, Leslie's had told me that my CYA was at 60, with this kit, i follow the instructions and i start putting solution until the black dot disappears right? well i filled up the tube all the way and i still saw the black dot, meaning that i don't have any CYA right? and stupid leslie's made me buy a four pound of CYA powder. Thank you and i am sorry i don't understand much about these things. thank you.
Click to expand...

Start here if you haven't already http://www.troublefreepool.com/content/213-extended-test-kit-directions

For the chlorine test only fill to 10 ml not 25 to start. You will use less drops this way. But you are doing it correctly, make sure you swirl the liquid after each drop it will turn from pink to clear. Keep adding drops until the color doesn't change anymore and then subtract 1. Meaning you may think it looks clear after 10 drops but if you add one more drop it may get even clearer, once it doesn't get any clearer you know the previous drop was the correct amount. So if you add 12 drops and it didn't get any clearer then it did with 11 drops, use 11 as your total drops. If you are using a 10 ml sample then divide this number by 2. So in this example 11/2 is 5.5 ppm.

20 drops using a 25ml sample is not unusual because you then divide that number by 4 to get the FC. So you stopped at 20 which would have been 5 ppm, you obviously have more than 5ppm because it was still pink. Like I said though use the 10 ml sample first.

Correct with the calcium hardness, you multiply the drops by 10 but make sure you are using the correct volume of water and follow the same color change technique as I mentioned above.

The CYA I don't know why there would be such a difference other than I don't trust the pool store. Try the test again make sure you are following the directions carefully. But you are correct, you should not see the dot. Did you fill the water to the first line then add the reagent to the second like and shake for 30 seconds? Do not add whatever leslies gave you until you test again. 60 is ok so im not sure why they gave you anything anyway.
 
Hi Mijmic. The pool stores' results can be due to a number of reasons. The machines themselves are capable of testing properly and better than any manual test kit (not because of the test kit but because of the human error potential is much greater with a manual test kit). The problem with pool stores is that they likely do not run regular controls on the machines. A pool store using a testing analyzer should be running control samples to ensure that the machine is capable of testing properly. Think of getting blood work done at a hospital. The machines they use are very accurate and they spend a lot of time and money to ensure they are working properly (calibrated daily, control samples run several times per day depending on machine). A pool store wouldn't do this. They have machines that have the capability to be accurate but they don't invest the resources to be sure they are operating properly. That being said even the same type machine in a hospital lab will test different than the same make/model right next to it, testing the same sample. There is an acceptable variance. I don't trust pool stores because they likely don't run control samples to double check the results. If I owned a pool store I'd print and post my daily calibration and control results and explain to people why I know my machine is accurate. I've never seen this though. Perhaps the machines made for pool water testing don't have such a capability??? If that's the case they have proven my point of why I don't trust them. Just my .02 on why I don't bring water there. Thanks
 

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