Leslie's Automatic Tester

[Romoth]

Please don't shoot me for what I'm about to ask, but I'm always interested in finding something to test my results against. The Leslie's down the road from us has "upgraded"(?) their tester to an electronic test. The results against mine have been very close but for CH. CH they had 480 and I was in the 400 range on my home test. Otherwise the differences were basically noise. Does anyone have strong feelings one way or the other on this as something to test my results against, or am I just adding headaches for myself?

 

[Jimrahbe]

R,

Being automatic does not necessarily mean it is more accurate..

If you take the same sample to 5 pool stores, you will most likely get five different results..

The problem with letting others test your water is who's test are you going to believe???

But then I am a little biased, as I would not walk into a Leslie's to just use there restroom, much less let them test my pool water..

Does your test setup include the speed-stir or similar mixer?? I find that without it, my tests are harder to do and not as accurate and repeatable..

Thanks,

Jim R.

 

[Romoth]

Thanks for the input, I'm not sure of the technicalities of the test, so thought I'd ask if it's more accurate than the normal drop test (or at least less prone to their errors). I was primarily looking to have a reasonableness check on the CH because sometime last year I think I had bad reagents and my CH was about 150 PPM higher than I thought it was and I had decent scaling issues. I appreciate the insight though!

 

[joboo7777]

I believe the Lamotte spintouch tests Total Hardness vs Calcium Hardness. Which may be the reason it’s different.

 

[Donldson]

These systems exist to present the aura of accuracy, not to be any more accurate. To be blunt, they are designed to get people in to the stores and buying products. Whether they are accurate or not does not affect this end goal so isn't really a concern to the people who operate it.

A response I've shared before about their reliability:

No. Those units are almost never calibrated once they hit the store because it doesn't matter if they are calibrated so long as they help push sales. And they do push sales, because a shiny technical looking device convinces people more than some salesperson with a test kit. And don't fall for that imaginary precision, that's literally added to convince people it is accurate. It cannot measure down to the single digit ppm CYA. Digital pool store testing is less reliable than typical pool store testing. Which, as you know, is unreliable.

Trust yourself and don't go seeking "second opinions" from pool stores. If you think you screwed something up, you can always ask here. When have we ever shied away from telling someone they were wrong?

 

[sacredcow]

I believe the Lamotte spintouch tests Total Hardness vs Calcium Hardness. Which may be the reason it’s different.

This. If there's any magnesium present, it may read as hardness depending on the specifics of the test.

 

[Romoth]

This is all absolutely fascinating. For real. Thanks for the additional information. The accountant in me would love to attempt to reconcile the results (i.e. magnesium), but it sounds like there are just way too many variables to manage. With the name of the Lamonte Spindisk was able to find several other threads discussing it.

Out of curiosity, how would I see if there's magnesium present, and would it have any impact on scaling or CH that i need to be aware of?

 

[mguzzy]

Another variable to consider in your accountancy, is that you have no control over who else getting tested. I have always been appalled at the procedures my local Leslie's uses. They rinse the test vials out with the last persons sample, and considered ready to go for the next guy. If I balanced my check book like that I would never reconcile anything.

 

[Romoth]

As a month old update, I was finally able to actually reconcile the difference to reasonable accuracy. I was reporting 350, Leslie's was reporting 385. I'm still getting scaling issues in several places, so decided to start really narrowing down parameters of failure. I made (in retrospect) a stupid assumption that the Taylor Speed Stir's tube was calibrated for the stirring "bean" that came with it. From what I can tell, it assumes you will add in water then the bean. On a 10ml test, that's about a 10% miscount and 350x1.1 = 385. I came out on an updated test at 400CH after doing it correctly. Wanted to post an update in case this was of interest to anyone else.

 

[KevJB]

Are you saying that adding the bean after you add the water will cause an error?

 

[Jimrahbe]

Kev,

Adding water to the proper level and then adding the bean is the correct way...

Adding the bean and then water is what gives an error.

Thanks,

Jim R.

 

[KevJB]

Cool - thanks!

 

[AUSpool]

This is all absolutely fascinating. For real. Thanks for the additional information. The accountant in me would love to attempt to reconcile the results (i.e. magnesium), but it sounds like there are just way too many variables to manage. With the name of the Lamonte Spindisk was able to find several other threads discussing it.

Out of curiosity, how would I see if there's magnesium present, and would it have any impact on scaling or CH that i need to be aware of?

To test for magnesium you would need a magnesium test kit but for most of us there is really no need. Magnesium is way more soluble than calcium and has no impact on scaling.

 

[Romoth]

Adding water to the proper level and then adding the bean is the correct way...

Adding the bean and then water is what gives an error.

It seems obvious is retrospect, but that was definitely the cause of my error!