I am a new pool owner (have had water in it for about 4.5 months) - being technically trained (engineer) I quickly decided I did not want to rely on colors or drop counting for accuracy of my pool chemistry. I bought a mobil spin tester and have been generally satisfied. However I have noted that the spin tester reports CH about 100 points consistiently low - compared to reagent testing with Taylor kit - I have also had compared at a pool store. Has anyone else noticed this - its also off on salt but the manual talks about that error (also low)....
Accuracy of Lamotte Spin Tester
- Thread starter Jffarraro
- Start date
Hi there Jffarraro, welcome to TFP 
As to your question... I'd go with the drop counting and color changes myself.
Maddie
As to your question... I'd go with the drop counting and color changes myself.
Maddie
- Jul 21, 2013
- 53,016
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Welcome to TFP.
As an engineer you understand the difference between accuracy and precision. The drop chemical tests that have a defined color change endpoint are the most accurate. Pool store test may give you the most precision with inaccurate results.
What chemicals test kit did you try using?
As an engineer you understand the difference between accuracy and precision. The drop chemical tests that have a defined color change endpoint are the most accurate. Pool store test may give you the most precision with inaccurate results.
What chemicals test kit did you try using?
Hi - yes, accuracy and precision are different but I had hoped to get good enough accuracy with precision - its easy to mis count drops and use the wrong light under which you evaluate color changes. The Lamotte water linik spin tester uses photodiodes to asses color and is reported to be very accurate and precise. I cant speak for the breadth of the results for pool chemical stores except that I know they are limited by the skill of the person doing the test. Generally the spin tester is an exact match for pH, TA, FC, CC, Borates, and CYA - its only off on salinity and CH - interesting because both are related to TDS at least indirectly. I know the salt is off because I bought a labratory grade, temperature compensated and calibrated TDS probe - I’ve used this reading to calibrate the readout on my SWG recently. I was curious if anyone in the fourm who uses the Lamotte tester has had a similar experience. I understand water chemistry (I work in the oil industry where formation water is an important factor in my work) I’m just trying to better understand the limits of the systems available to the home owner for measuring these parameters. I do have a call into Lamotte - hopefully they will be able to give me some insight on the accuracy of their test equipment - (which is sort of important given it was a large investment). For refernce the Taylor Kit was the K-2006.
- Jul 21, 2013
- 53,016
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Most people don't have a problem counting 10 to 20 drops. The FAS/DPD test is a color change from red to clear. The TA test is a change from green to blue. The CH test is from red to blue. Those color changes are not very subjective although some may be difficult for folks with various color blindness.
The best test for salt is K-1766 Taylor Salt Test . My $20 salt meter from Amazon reads about 200ppm low compared to my K-1766 salt test.
Do you use the Speedstir Magnetic Stirrer with your K-2006? Good stirring over swirling the vial does make a difference in the accuracy of the tests.
If you use the top search bar for "Lamotte Spin Tester" then click Google Search you will find many other discussions here about it.
The spin disk was brought about to simplify testing at store level, plus its read out suggest what chemicals are required. So a relative new worker could run their water lab. I have personally found it to be incredibly inaccurate on ph, salinity and ch.
Plus those disks are not cheap for pool stores, depending on where they buy them, they can cost upwards of $2 a unit. Someone’s going to pay for those in the end. We costed out titration and it was $0.60 a test.
Plus those disks are not cheap for pool stores, depending on where they buy them, they can cost upwards of $2 a unit. Someone’s going to pay for those in the end. We costed out titration and it was $0.60 a test.
Uh huh.... those "free" tests often cost more than one thinks!
Those disks are expensive - I’m paying retail for them (I’d assume a store is getting a better deal); I’m using single use disks with 10 factors tested. They cost $127 for for 50 so about $2.50 per disk. But I’m not passing any costs on ...its all on me so at least its transparent.....- and I use one a week, sometimes 2. It is fast. I have found it to be VERY accurate for pH, TA, FC, CC and CYA (compared to Taylor kit I run myself) - it has problems with CH and Salt. Lamotte has offered to remotely connect to meter to trouble shoot it - so far there customer service has been good. I’m also an engineer with a graduate degree running this at home - I’d imagine the avg pool store employee is not anywhere as meticulous about cleanliness of the disk, accurate filling of the disk or calibration of the machine. I’m sure my spin tester resuslts are more reliable than what you’ll get at a store.
I can only say from experience of using it thousands of times that it’s not accurate. They have a “recalibration” disk that is supposed to be used regularly and that didn’t change results. Plus if your chlorine is high, which you could detect with one titration test, you wasted a disk and the remaining results are inaccurate as well.
We are always trying to reinvent the wheel, but titration, performed by the same person will give more consistent results imo.
We are always trying to reinvent the wheel, but titration, performed by the same person will give more consistent results imo.
Wobblerlorri
Bronze Supporter
- Apr 16, 2019
- 2,010
- Pool Size
- 4024
- Surface
- Vinyl
- Chlorine
- Liquid Chlorine
I have a degree in Biology and minor in Chemistry, with a concentration in Microbiology, so I'm very used to titration and colorimetric testing. It's my considered opinion that the titration and colorimetric tests we use with the kits are far more accurate and reproducible than any thing a pool store uses. Besides, to properly use the Lamotte device there has to be calibration and education done with personnel to insure accurate results. I've seen no evidence of either of these things happening in a pool store.
As for price, my local pool store passes on the cost directly -- they now charge $25 per test if you don't buy anything worth at least $50. What a rip-off, I say.
As for price, my local pool store passes on the cost directly -- they now charge $25 per test if you don't buy anything worth at least $50. What a rip-off, I say.
Last edited:
Wobblerlorri
Bronze Supporter
- Apr 16, 2019
- 2,010
- Pool Size
- 4024
- Surface
- Vinyl
- Chlorine
- Liquid Chlorine
OMGosh! $25!??!?! That's obscene! What if all you need is a $10 chemical?!!
Maddie
LOL there's nothing in my pool store that costs $10! if there were, you'd have to pay for the test AND the item! Or buy $50 in product to get the test for free.
It's a racket, that's for sure. I don't darken their door.