Test Kits and Accuracy - Whom to Believe

[johnsimion]

After getting what I thought were ridiculous results from the pool store, I bought a LaMotte 2056 ColorQ Pro 7 test kit which I find pretty easy to use and I'm very careful to follow the instructions to the letter. However, I have read in this forum that the ColorQ isn't necessarily accurate, either, and that I should get a Taylor kit. But how would anyone know which one is accurate? How could you prove accuracy of one versus another?

I know my water is out of whack. I'm planning to drain and replace it next week, but that's another issue. Meanwhile, I'm watching my neighbor's pool. Since he and I got our pools finished and set up at nearly the same time (March 2014) by the same builder and with nearly the same equipment, I thought I'd run a little comparison (the only differences are that I have an in-floor cleaner, I'm shaded, and have solar, whereas he is mostly sunny). We both have inline chlorinators. I would have expected somewhat similar results, and I suspected he would also have high CYA buildup just like me. My neighbor doesn't have the big calcium buildup that I do. My own pool has enough calcium buildup that I'm having it bead blasted when I drain it down. I spent a fortune on these nice beautiful boulders and it just irks me to see that &#&@#* calcium on them within six months!

"Because I could," I ran tests on his water and my own, and also ran samples to the pool store to get their opinion as well (BTW, both pools are sparkling clear with no algae whatsoever). Here are the results (my LaMotte results first, pool store results in parentheses):
My Pool: Temp 85, FC 7.88 (8.4), TC 7.88 (8.4), PH 7.5 (8.1), TA 61 (110), CH 308 (475), CYA 108 (160). Pool store reports Langelier Index of 0.94. Pool store tells me to remove chlorine and add 3 pts 4 oz of acid, but I know from experience that such a small amount of acid has virtually no effect, probably due to the excessive CYA.
Neighbor: Temp 84, FC 5.15 (8.4), TC 5.15 (8.4), PH 7.2 (7.6), TA 54 (95), CH 283 (450), CYA 103 (110). Pool store reports Langelier Index of 0.37. To further complicate matters, my neighbor has a pool service that also tested his water earlier today and they texted him that his CYA level is 76, so they see no problem (I don't yet have his other results from the service).

Looking at these results, whom do I believe? I guess I could buy the Taylor test kit just to confuse matters further, but how would I know THAT is accurate, either? I guess I could then take three results and roll the dice to see which one I want to believe. The only thing I can say right now is that my CH and CYA are too high according to both tests, which is why I'm going to drain 75% of the water next week and refill with as much soft water as I can generate. I want the fewest chemicals possible and I never want to see the darned calcium buildup again if I don't have to, so the decision to drain and refill is easy for me. But do I advise my neighbor to drain and refill his own pool? Even his CH and CYA are pretty high ... aren't they? Seems to me that he is probably accumulating calcium as well, although I think he scrubs it off his tiles so maybe I just don't see it. Personally I think both pools were incorrectly set up by the builder and the problems have been compounded by the trichlor tablets.

But again, no one around here seems to care, everyone else I know in this town just keeps on popping tablets for three or four years until there is so much CYA that the chlorine won't work any more. I like to actually get in my pool and not have my eyes burn and my skin get all dried out, which is why I care. I should learn not to care, I'd get less stressed out.

 

[tim5055]

I would trust a FAS-DPD test with Taylor chemicals. Several folks here have the LaMotte ColorQ and report issues with it and reliable testing. It seems to work well for FC and pH but CYA results have been described as "erratic". Jason has advised in the past to follow the instructions very carefully for better results.

I wish I had a better answer for you

 

[Divin Dave]

Hi Johnsimion,
There are literally 1000's of people on this forum who use the Taylor Kit and/or the TF100 kit. TF 100 uses Taylor test regeants.
The test kits work well, and our sparkling clear pools are proof of that.

The main difference between the two kits is that the TF 100 has larger volumes of regents, which result in being able to do more test. Its the best bang for the buck.
www.tftestkits.net

Next, Pool Store Testing is notoriously incorrect. Thats all there is to and those tests are preformed by people who have no clue as to proper pool chemistry. There extent of knowledge is what some smooth talking chemical salesman tells them.

I dont know much about the ColorQ... or how the test is performed. I apologieze for that, but I would trust it longgg before I trusted the pool store.

The Taylor and TF 100 tests change color. Example when you do TA test, the color changes from Blue Green to Red. Count the number of drops and multiply by 10. There is no doubt such as the types of tests where you have to compare shades of the same color.

I dont know if this helps ease your mind or not, but i hope it does. You simply cannot go wrong with either the taylor or the TF 100... and tftestkits guarantees their testing regeants are fresh. If you find one that is not performing, they will immediately replace it at no charge.

 

[Kiss4aFrog]

The ColorQ Pro 7 only reads to 10ppm FC so it wouldn't really be too helpful for SLAM unless you have almost no CYA. http://www.lamotte.com/en/pool-spa/digital-testing/colorq/2056.html

Previous thread asking about feedback on the LaMotte kit : http://www.troublefreepool.com/threads/56209-Need-Feedback-on-the-LaMotte-2056-colorQ

IMHO, when it's time to get replacement reagents, upgrade to a K-2006 or better yet the TF-100 and I'd highly recommend the Speedstir http://tftestkits.net/SpeedStir-Magnetic-Stirrer-p56.html Video of it in action https://www.youtube.com/watch?v=4_EJknrPjYE&list=UUNFkPFCkt9Y_YYNAeLtUr1g&noredirect=1

 

[johnsimion]

"The Taylor and TF 100 tests change color. Example when you do TA test, the color changes from Blue to Red. Count the number of drops and multiply by 10. There is no doubt such as the types of tests where you have to compare shades of the same color."

This part makes sense to me as far as reading the result consistently but does not prove that the underlying test itself is any more accurate. I read the other thread, notably the parts that say "some of the tests are not reliable" and "small photometers tend to be cheap and inaccurate." What is the scientific basis for either conclusion? Aren't both products designed and built by scientists and chemists? We're in agreement that the pool store results are probably inaccurate, but that's because we can see them slop through their results. But when carefully following the test procedures and using fresh reagents and getting consistent results, I'm not seeing a basis to conclude that Test X is better than Test Y. There may actually be such a basis, but I'm not seeing it.

Moreover, I don't see any logical basis to conclude that a small, cheap photometer is inaccurate. Any photometer is just reading the amount of light that passes through a sample. Whether it's cheap or not, it WILL be consistent because it's a machine. It doesn't wake up grumpy in the morning with bleary eyes, it always measures light the exact same way, and it's not subjective. In fact, my own results using the LaMotte have been remarkably consistent, if I test daily I will get practically the same result daily. It's a consistent result, but not necessarily an accurate result. The photometer test procedure itself may be wildly inaccurate, but without actual scientific evidence, I see another unsubstantiated conclusion.

The message I'm getting is twofold. First, I ought to use the same test kit every time, because right or wrong, at least that way my results are consistent. Second, the only proof of success is if the pool is clear and doesn't burn your eyes or dry your skin out.

 

[tim5055]

When it comes down to it you are the one that has to be happy with your decision and I really hope it works out well for you. Almost to a person, everyone here uses a Taylor based FAS-DPD test kit. You probably won't find many here who can give you any more information on you ColorQ other than Jason and/or chem geek.

To quote Dave, Site Owner of TFP:

You may or may not choose to use these methods and guidelines or you may use some and not others. Our goal is to teach you what has been proven time and time again and then let you use that information to your benefit.

You are correct that your neighbors pool is out of whack also (high CYA) but talking to him about it will depend on your relationship with him.

 

[jblizzle]

Report back in a few months and let us know if the color q stays consistent. There have been at least a handful of members that eventually gave up with using it as the results would occasionally be off ... resulting in doubts and always having to test at least twice.

The other major downside is the limitation of the FC to 10 ... worthless I'd you need to SLAM.

 

[chem geek]

You can at least partially validate a test kit by measuring against known standards. Such standards exist for 100 ppm TA, 200 ppm CH, and 50 ppm CYA. You can get pH 7.01 Buffer Solution, pH 7.41 Standard Solution (also pH 7.413 Standard Solution). You can also get 25-30 ppm chlorine standard solutions and 2.0 ppm standard solutions.

We know the Taylor tests are accurate not only because they perform well against standard solutions, but because they perform well against measured tap water and against calculated dosages of chemicals into known volumes.

 

[Billrector]

I may be one of the rare people who has both the TF-100 and the ColorQ. I have had the ColorQ for about a year and find it VERY ways to use compared to the TF-100. Regarding accuracy, I have had no reason to question the ColorQ results especially the CYA reading (where others report it being erratic). I have a year of weekly tests and watch week is consistent with the prior week and I have seen zero erratic readings. The only accuracy issue I have seen is with FC and TC. Lately, I have questioned these readings because I have gotten readings that I felt made no sense (FC higher than the prior day). I got to the point I would do repeated tests and I would get different readings.

At ths point I bought the TF-100 since as one other poster pointed out, you need this to SLAM anyway. I also bought new reagents and test tubes for the ColorQ. The new test tubes seem to have cured the occasional Er7 on the ColorQ also. Currently, I'm getting very similar results from the two devices.

At this point, I use the ColorQ for daily tests and the TF-100 for my weekly test.

 

[Swampwoman]

The thing that strikes me about this thread isn't the test kits....(I use Taylor, btw). It's that two of you have brand new pools as of March, both with more than 100 pm cya already. It's kinda sad to know you've both been set up to struggle instead of just enjoying a trouble free pool

If you switch to TFP method and get it down to the 5-min/day science its meant to be, it won't matter what your neighbor does, because YOU will be able to tell the difference in your water I have lots of pals who think their pools are clear and fine. My own observation is that you don't really know what you're missing until you've had it Those "clear and fine" folks will marvel at my water and can't figure out why it feels different when they're visiting. Some will undertake the TFP journey, and others won't.

Doesn't matter. My water matters to ME and those I invite to swim. So with your new pool, don't worry about what your neighbor's doing...just get yourself set up to enjoy it more and wrestle with it less

 

[Griswald]

There is a difference between accuracy and repeatability. If a test is accurate, but you get different results every time, it is not repeatable. However, if your tests indicate a CYA of 50 (or very close to it) every time, you probably have a better chance at controlling the water chemistry.

Who really cares if your FC is 6.89 or 7.01 or 7.03, as long as it stays at whatever reading keeps your pool clean and the green away.

I think the Taylor kit is very repeatable, (and it may be very accurate too) due to the simple method of counting drops and that's why it is recommended. Its very easy to tell if something changed between readings, unlike a color match system.

It's a six-sigma thing...

 

[Bama Rambler]

I don't know what made me stop and read this, but I did!

While I think you should consider getting a FAS-DPD and CYA test, it's not imperative. The larger thing that jumped out at me is that you're having calcium build up with the CH at only 300! I plugged your numbers into PoolMath and your CSI is -.43. You shouldn't have any scaling at that level.

Are you sure it's calcium or could it be something else. Efflorescence maybe? or salt build up? Do you know what your salt level is?
If it truly is calcium scaling then I'd seriously question the tests you've seen.

I also plugged the pool store numbers into PoolMath and got a CSI of .6 which would cause scaling in your pool. Maybe getting a TF-100 wouldn't be such a bad idea! :???:

 

[kcindc]

I use the TF-100 and friends who have pools marvel at my sparkly water and they love the way my water feels. I've only owned a pool for 3 years and some of these friends have owned a pool for 20+ years.

I try to tell them about the TFP method and using a reliable test kit (TF-100 or the K-2006) and their eyes glaze over.

I am happy with the advice given here and I'm very satisfied with my TF-100.

We are hear to offer our experience voluntarily and without an interest in taking money from your wallet, it is up to you to decide whom to trust.

 

[JVTrain]

"Because I could," I ran tests on his water and my own, and also ran samples to the pool store to get their opinion as well (BTW, both pools are sparkling clear with no algae whatsoever). Here are the results (my LaMotte results first, pool store results in parentheses):
My Pool: Temp 85, FC 7.88 (8.4), TC 7.88 (8.4), PH 7.5 (8.1), TA 61 (110), CH 308 (475), CYA 108 (160). Pool store reports Langelier Index of 0.94. Pool store tells me to remove chlorine and add 3 pts 4 oz of acid, but I know from experience that such a small amount of acid has virtually no effect, probably due to the excessive CYA.
Neighbor: Temp 84, FC 5.15 (8.4), TC 5.15 (8.4), PH 7.2 (7.6), TA 54 (95), CH 283 (450), CYA 103 (110). Pool store reports Langelier Index of 0.37. To further complicate matters, my neighbor has a pool service that also tested his water earlier today and they texted him that his CYA level is 76, so they see no problem (I don't yet have his other results from the service).

Electronic devices that measure anything require regular calibration and a calibration verification sample should be run periodically to make sure it is within calibration limits. Drop based tests are inherently calibrated as long as they are manufactured with quality chemicals and procedures and stored properly. Improperly calibrated and unverfified calibration can lead us down very dark alleys in terms of making decisions based on results in my experience in laboratories. The "built in" calibration and simplicity of the drop based (titration) testing is a much bigger draw for me than whizbang extra significant digits that aren't needed.

Testing methods aside, your numbers, using the LaMotte results. If you plug all your readings into Pool Math (we don't know Salt level so I used 500, Borates assumed 0) your current CSI is -0.44, which is actually indicative of being potentially corrosive to plaster, the opposite of what you're seeing, calcium build up. Your CH is actually not high. You're on the high side of the recommended range (250-350), but it is manageable at that level. If you kept everything the same but lowered your CYA to 50 and raised TA to 80, you would have a CSI of -0.04, as close as you can get to balanced for your plaster. Your current numbers don't explain the scaling you're seeing. In the past few months perhaps your pH was consistently higher, your CYA lower... (I'm just throwing out guesses here) ... that may have led to the scaling you're seeing.

Your neighbors CH is fine but their CYA is certainly high and I haven't plugged in their numbers but based on their lower pH, lower TA and lower CH, I'd say they are in the potential to be corrosive range as well.

 

[johnsimion]

Let me clarify a couple of things. I **currently** have an inline feeder using trichlor tablets. I wanted a SWG like I used to have in Florida. We loved the one we had in Florida, but the pool builder talked me out of it because (he said) they don't work under 50 degrees and the inline feeder would be soooo easy. I never gave a second thought about CYA (stabilizer) because in Florida we had to add stabilizer all the time with the SWG.

When the pool was set up in March, the pool builder added a gallon of liquid stabilizer (enough for 10,000 gallons vs. my pool is 19,000). He also set the feeder at "5", which was at my (ignorant) request because the feeder wasn't really dissolving any tablets at first. Yeah, it was winter -- I know that now, but I thought the low feed setting was a problem at the time. And then at my request they also increased the speed of the pump so the in-floor cleaner would work better. I am sure this is why the FC and CYA levels have been increasing for months, and that's probably why the calcium built up as well.

I freely admit ignorance. I didn't even know there was stabilizer (CYA) in the tablets, and when I did learn, I thought it was a good thing because my Florida mentality thought, "Gee, now I don't have to add stabilizer!" I had no idea that the stuff actually builds up here in Vegas! But I also have to say that the so-called professionals around here aren't very helpful. I mean, they knew I was new here and they could have mentioned the buildup issue. And why was the pool builder adding stabilizer from Day One and then willingly going along with raising my feed rate? Again, not one word about CYA buildup. The mentality here is just to use the tablets until the CYA and FC get so high that the chlorine won't work any more, then they just drain, refill, and start over again, and I really think they don't even understand why they are doing it! Just yesterday when I was at the pool store, I mentioned to the manager that I was considering putting in a SWG and he said, "You don't want to do that, they don't work under 50 degrees." I know this to be false because I've read a manufacturer's instruction booklet on the subject and it said that the problem in winter is that the SWG might either (a) freeze if water doesn't circulate (not a problem in Vegas), or (b) generate too much chlorine in winter and necessitate being set to a very low setting (also not a problem). But neither the pool builder nor the pool store is saying that!

As for my neighbor, he is a good friend and I can tell him anything, but he is using a pool service that is also ignoring the problem (typical!). He is also in denial since he is dealing with all kinds of other house problems such as leaky watering system, so I won't be surprised if he ignores me ... but eventually he'll come around.

I hope my posts don't sound like I'm being critical of you VERY nice people, you are the only people who actually seem to know anything, it's just that I've gotten so much misinformation that any more I'm having a hard time believing anything!

 

[chem geek]

Any test method can have errors, of course. For the Taylor tests (remember the TFTestkits TF-100 uses Taylor reagents) and in general drop-based tests, the errors come mostly from the following:

• Drop size. This can be affected by static electricity and minimized by wiping the dropper tip by a moist cloth/tissue. The dropper tip can affect the drop size and the bottle should be held vertically. For the Taylor tests, there should be 24 drops/ml.
• Sample volume. There may be some error in the sample tube volume markings or in user measurement. One should measure from the bottom of the meniscus in the middle of the tube.
• Titrating reagent concentration. There may be error in the concentration of reagent, either initially or over time. This is usually the smallest error as the reagents are made very accurately and most are acids or bases that are stable. The exception to this is the FAS reagent that must be kept away from light and not be exposed to higher temperatures. See Recognizing a Compromised Reagent.
• Interference. Some potential interferences are listed by Taylor.

For the titrating tests, the usual error bounds are +/- 1 titrating drop or 10% of the reading, whichever is greater. In practice, one can usually get repeatability within 5%.

For the pH test, there are errors associated with color matching and with the colors in the comparator tube. For the CYA test, it's a visual turbidimetric test that depends on lighting conditions where the standard is strong indirect light (i.e. outside on a sunny day with one's back to the sun looking down into the tube shaded by your body).

 

[tim5055]

I freely admit ignorance. I didn't even know there was stabilizer (CYA) in the tablets, and when I did learn, I thought it was a good thing because my Florida mentality thought, "Gee, now I don't have to add stabilizer!" I had no idea that the stuff actually builds up here in Vegas! But I also have to say that the so-called professionals around here aren't very helpful. I mean, they knew I was new here and they could have mentioned the buildup issue. And why was the pool builder adding stabilizer from Day One and then willingly going along with raising my feed rate? Again, not one word about CYA buildup. The mentality here is just to use the tablets until the CYA and FC get so high that the chlorine won't work any more, then they just drain, refill, and start over again, and I really think they don't even understand why they are doing it! Just yesterday when I was at the pool store, I mentioned to the manager that I was considering putting in a SWG and he said, "You don't want to do that, they don't work under 50 degrees." I know this to be false because I've read a manufacturer's instruction booklet on the subject and it said that the problem in winter is that the SWG might either (a) freeze if water doesn't circulate (not a problem in Vegas), or (b) generate too much chlorine in winter and necessitate being set to a very low setting (also not a problem). But neither the pool builder nor the pool store is saying that!

As for my neighbor, he is a good friend and I can tell him anything, but he is using a pool service that is also ignoring the problem (typical!). He is also in denial since he is dealing with all kinds of other house problems such as leaky watering system, so I won't be surprised if he ignores me ... but eventually he'll come around.

I hope my posts don't sound like I'm being critical of you VERY nice people, you are the only people who actually seem to know anything, it's just that I've gotten so much misinformation that any more I'm having a hard time believing anything!

I would say most people who show up here (like me) had no idea of the FC/CYA relationship because the pool industry doesn't think it's a problem. The last time I had my water tested at a store (kind of like you, comparing my results to theirs) the print out said CYA up to 200 was fine and to keep my FC 1 - 3. This is what they are taught and keep going along with it. I'm sure there a few store owners out there who understand and do the right thing by their customers and there are a few who understand and see that they can make money in magic potions when folks have problems. The vast majority just keep doing the same thing day after day and don't really study the problems and look for a solution.

As your neighbor is a friend work with him. But, just like here on the forum it is a very fine line to walk at times when you try to help folks and not get them mad at the same time.

To be honest, I was having a hard time understanding where you were coming from on your first couple of posts, but probably because the web removes the facial expressions and tone/inflection of voice that we generally get a lot of information about a person from.

Stick around and I hope we can help you so you can pass it along to your neighbor and others.

It would help us if you would add the following information to your signature for future posts:

• The size of your pool in gallons
  
• If your pool is an AG (above ground) or IG (in ground)
  
• If it's IG, tell us if it's vinyl, plaster/pebble, or fiberglass
  
• The type of filter you have (sand, DE, cartridge) and, if you know, the brand and model of the filter.
  
• If you know, please tell us the brand and model of the pump, and mention if is it a two speed or variable speed pump.
  
• Date of pool build/install, particularly important if less then a year old.
  
• What kind/model of water test kit you are using
  
• Other significant accessories or options, such as a spa , SWG, or cleaner

 

[timerguy]

As for a SWG not generating below 50 degrees, That's probably true for most SWGs as water temps below 50 aren't conducive to growing algae. You may have to add a small dose of Bleach occasionally. I don't think i used any more than 3 gallons of bleach the whole winter here last year.

 

[Billrector]

Electronic devices that measure anything require regular calibration and a calibration verification sample should be run periodically to make sure it is within calibration limits

I don't believe this is necessary for the accuracy we need to maintain a pool! When was the last time you had you thermometer calibrated, or you car speedometer, or your multimeter? I've never had any of these calibrated and I (and you) use them all the time. We aren't looking for 6-Sigma accuracy here.

 

[JVTrain]

:gone: