Water Test Equipment like the pool stores use

[dayhiker]

I think I had my water tested 3-4x before I realized I needed to start searching the 'net for a way to do my own testing. I stumbled on Ben's old site which led me here. My initial "mission" was to find the equipment the pool stores use. I was quickly re-directed to the BBB and the type of testing we all know and love. Just out of curiousity, where would you buy or price the equipment that they use? Also, people have readily given examples of the wide spread in the results they see. Is the way done here actually more accurate?

For the record, I do own and use the TFT kit. As I've dealt with iron stains then an algae outbreak it seems that I perpetually have the kit out with various beakers out to dry. I'm fairly sure my wife is sick of seeing all of this out and about, hence the curiosity.

Thanks.

 

[duraleigh]

Dayhiker,

Waterbear is the testing guru and can answer your question thoroughly.

Just to say what little I know, Your testing will be far more accurate than most pool stores. Their equipment is designed for speed and simplicity....not accuracy. Waterbear often says their equipment is also designed to sell products, too.

Anyway, I'm sure he'll see this and have some real insight for you.

 

[dayhiker]

Thanks. When I first bought my kit I figured it was a $70 versus $400??? issue. As I've read over the last year I've been wondering if it wasn't more of an accuracy thing.

I assume their testing is some sort of optical device?

 

[dmanb2b]

in some cases they use an optical device and sometimes they just use a plain old test strip...the key with using any test kit is that you use the same kit and method of testing as consistency has just as much to do with water balance as accuracy.

 

[Guest]

Last year was my first year caring for my pool. At first, I kept looking for easier ways to test. I looked into digital test strips, etc., but everywhere I went, the consensus was that they were not reliable unless you are willing to pay a really, really huge amount of money.

I bought the Taylor K-2006 last year, but since then have re-ordered refills from TFT. I really trust the tests, especially after gaining some experience using them.

 

[waste]

While we're waiting on Waterber, let me toss a couple of coins into this wishing well.

Many of the 'computerized' test stations are done by strip readers, the better ones are done with liquid reagents that the computer scans for more precise results, some stores (the Leslie's I went to for parts one time) have the biggest Taylor 2005 set up and did the titration tests as you or I would. The problem with all these set ups is tester ability! Did the tester dip the strip for the correct time and wait long enough before placing it in the reader? Did the tester put the proper amount into the test cell? Does the tester take the time to properly measure and mix the drops?

I certainly agree that the software with the computerized test systems have some 'sellware' in them! Though I've offered a number of times to compare my K 2005 (6) or TF 100 results to theirs on the same water sample, they've never been able to do that ("the computer is reloading", "we're too busy right now"... "we just noticed our strips are out of date") - I think they know that their testing is BS and don't want to be forced to admit it

I'm getting close to - so I'll leave this until Waterbear answers

 

[JasonLion]

The equipment used at many pool stores is much worse than the TF100. Many stores use systems based on test strips that are read by a computer system, which are far worse than the TF100. The only computerized test system in common use in stores that is in the same league is the LaMotte WaterLink® Express, and even that isn't a significant improvement on any of the tests and is noticeably worse on a few of them.

Many stores use drop based tests with the same Taylor chemistry that is used in the TF100. These tests can be as good as the results you get with a TF100, though in practice the person doing the test at the store is often rushed and/or untrained and may well make more mistakes than the average home owner would. Many stores also use the less expensive DPD chlorine test, instead of the FAS-DPD test included in the TF100, which lowers the precision and range of the chlorine test.

 

[mickey4paws]

When I first started learning how to use the TF100 and was still pretty nervous, I wanted to check my results to Leslie's. I very carefully watched them do the tests and couldn't believe they were miscounting the drops, had re-agents lying out on the counter with tops off, etc. I do not trust their results at all. They also did a salt test and when I mentioned how different their results were than mine, the guy admitted their device hadn't been calibrated in quite a while.

I had to go in there last week to buy a new skimmer basket and the guy asked why I hadn't been in to get my water tested lately. I replied that I do my own testing now and just smiled.

Hands down the best thing I ever did for my pool was get the TF100 and do my own testing. It's so nice not to be at the mercy of the pool stores.

 

[Guest]

am I late to the party again?

Having used 'computerized' testing systems in pool stores I can say without a doubt that either a TF100 or a Taylor K-2006 is going to provide much more accurate and precise results. Strip readers (such as the ALEX system and it's cousins) are useless because of the inherent problems with strips.
Colorimeters (such as LaMotte Waterlink and the Hach units) are a bit better BUT still suffer from limitations from the range of the meter and are not necessarily more precise. For example, the TA test on the Waterlink system will read low when the FC is above about 3 ppm according to LaMotte tech support. Conveniently this helps to sell a LOT of expensive baking soda labeled as alkalinity increaser and then helps to sell a lot of acid to then lower the resultant too high TA and the resultant too high pH the next time the customer comes in.
The CH test with the same unit will read low when the calcium hardness approaches the upper range of the meter, whihc is around 400 ppm. This means that someone could come in with over 600 ppm CH and the system will say their calicum is only around 300 ppm. I have seen this happen too many times for me to even trust the CH test in this $1000+ SYSTEM.
FWIW, the CYA test on this system has a precision of +10/-25 ppm which means it's more likely to read low than high (very convenient for selling trichlor) but, more importantly, has a precisionrange of 35 ppm! This is worse than the somewhat subjective dispappering dot test we all know and hate!
For those pool stores that are using Taylor labs or other drop based systems you are often at the mercy of employees who are really clueless as to what they are doing. I have seen titration tests ended before endpoint and one time I was having my water tested at a competing store just for fun and the young girl did a DPD test and wrote down 2 ppm. I knew it was higher and asked to see the comparator. I told her that it looked like 4 ppm to me (which it was) and asked for another opinion. The owner came over and verified 4 ppm.
Bottom line, learn to test properly and do your own testing.
Keep in mind that the fancy equipment in pool stores serves a few purposes that are not really in the best interest of the pool owner:
1. it looks impressive and gives a printout so it must be better, right? (NOT)
2. It is designed to allow a whole battery of tests in a minimum of time. The LaMotte system will test 8-10 water parameters in 3-5 minutes. Strip readers are even faster. Minimize the time spent testing and maximize the profits, that's the ticket. Accurate results? We don't need no steeenkin' accurate results!
3. it looks impressive and makes the employee look like he actually knows what he is doing (NOT)
4. it helps to sell a lot of chemicals because the printout says you need them and the computer is always right (NOT)
5. did I mention it looks impressive and it gives you a computer printout?

 

[dayhiker]

So, most stores are doing drops or strips, interesting. The local place I go to, and it's been over a year, puts a small sample in a little device and in about 30 seconds they print a sheet out with all of your readings. I keep meaning to take a sample of pool and tap water to them to try and figure out where my iron is coming from and how much of it I have. That's another thing that led me back to this question. Does the local place just have better equipment than the average joe or is this an instance where if it comes on a pretty printout and has too many significant digits then there is a perception of greater accuracy and precision?

 

[dayhiker]

I re-read waterbear. Sounds like the system I've seen is what he described, they just don't have to reload the strips each time maybe which leaves me ignorant that it's using them. Maybe there's a "clip" of strips that automatically reload.

Thanks for the education on all of this.

 

[Bama Rambler]

The place I've used a couple of times uses a strip reader. I'm very leary of their numbers. Last time I was there the guy just dipped the strip in my water and immediately stuck it in the reader. Their numbers were all over the place some were higher than mine some were lower and a couple were even close. I really only wanted the iron and copper tested. For that I was kinda impressed. They used individual strips and because "we don't normally run metals" they had to open a new kit for both. Of course I had zero but the good thing was I got to watch him do it and knew the strips were good (yeah I checked the date).

And lke Waterbear said their fancy printout wanted me to buy a whole slew of chemicals that I knew I didn't need. So I got them to fill my clorine jug (they charge you less if you bring your own jug) and I was on my way.

 

[Brad S]

The place i use sometimes has a spectrophotometer/cuvette system. The cuvettes have the reagent already added and come sealed on top with paper. The guy puts in a few hundred microliters (guessing on the volume here), mixes, and reads. My problem with it is i dont see it zeroed, nor do i think there is a way to calibrate the thing with standards every morning.

I usually test the water with my Taylor 2006 and then go and have them test it to see what the difference is. I find almost everything reads low with their system, except for the pH. It's usually right on with mine. It doesnt seem like he lets the tests develop properly. Couple of shakes and he sticks it in the spec. If its a Lamotte system, the instructions say the reagent should incubate for 2 minutes on most of these tests.

The last test i did was:

Taylor 2006 Pool store

FC 5.5 2.7
TA 70 58
CH 100 68
CYA 50 30
pH 7.6 7.7

 

[Guest]

The place i use sometimes has a spectrophotometer/cuvette system. The cuvettes have the reagent already added and come sealed on top with paper. The guy puts in a few hundred microliters (guessing on the volume here), mixes, and reads. My problem with it is i dont see it zeroed, nor do i think there is a way to calibrate the thing with standards every morning.
This sounds like either a LaMotte or a Hach Colorimeter and I am going to guess LaMotte since it it way more common. The vials are plastic and square and the pipette automatically dispenses 3 ml of water into each vial (if it's doen correctly) The first sameple run is a blank of plain pool water which is what the machine is zerod to. It looks impressive but I trust it a lot less than a drop based test.
I usually test the water with my Taylor 2006 and then go and have them test it to see what the difference is. I find almost everything reads low with their system, except for the pH. It's usually right on with mine. It doesnt seem like he lets the tests develop properly. Couple of shakes and he sticks it in the spec. If its a Lamotte system, the instructions say the reagent should incubate for 2 minutes on most of these tests.
Wrong, if it's a LaMotte the different tests have different timings. First, the blank is run and all vials are filled in proper order ,the vials are not to be shaken but inverted 3 times right before being read, FC is read immediately (before 30 seconds), TC is read at one minute, then pH, CH and TA at 1.5 minutes, then CYA and Iron at 2 and the rest at 3 minutes and before 5 (copper and the optional nitrate and borate tests). There are several interferences that the operator needs to know with this system that most do not unless they have passed the LaMotte certification exam for the system. The online instructions for this system are just the quick start card that sits on counter and do not have the full instructions such as the acid/base demand tests or when LaMotte says to do a dilution or drop test to get correct results because water parameters are out of range of the meter or reagents used in this system. The pH test is the most accurate of the tests, IMHO.
The last test i did was:

Taylor 2006 Pool store

FC 5.5 2.7
TA 70 58 This is what happens when FC is abouve 3 ppm
CH 100 68 This is what happens when this test is read too early
CYA 50 30 This is within spec. The precision of this test is +10/-25 ppm and the store test is only 20 ppm lower)
pH 7.6 7.7

 

[Brad S]

I appreciate the explaination.

 

[dayhiker]

Brad S described pretty what I was seeing at my place. I assumed it was some sort of spectrometer until the talk of test strips came up, then I figured maybe a spectrometer was something you wouldn't have on such a small level. Heck, I 've never seen one, just heard about it mentioned in astronomy magazines and way back in college chemistry.

 

[Guest]

The unit is a colorimeter or photometer, depending on what the manufacturer calls it. They are basically the same, although the first is more accurate description, IMHO since they are measuring the absorbance of particular wavelengths of light by a specific solution which is the definition of a colorimeter. Photometer is just a light meter of any type and can include such things as the light meter in a camera.
Those units that test CYA are also turbidimeters (not all do).