I've been using the resources of this forum for quite a while now to understand the water chemistry for our in-ground spa and I have to say that it's an incredibly useful resource. So far I've always been able to find the answers I need. Until now.
I recently, last week, drained and re-filled the spa. While I was at a local store grabbing my big bag of salt, I noticed that they had some products I hadn't seen before called: MySaltPool, supposedly designed specifically for SWG systems. So I grabbed a bottle of something called "Salt Cell Protector" and added some when refilling the spa, which BTW is about 1,000 gallons. According to the bottle, it contains polymaleic acid and phosphonic acid.
Since then, the salt reading I get using the Taylor test (K-1766) is around 800ppm higher than the Aquapure reading. The Aquapure shows 3,400 and the Taylor test around 4,200. I also took a water sample to my local store and they also had a reading of 3,400. Prior to this, I have used the same store and have always had results within 200ppm of both my Aquapure and my own Taylor testing.
So, I guess my question is which of the testing methods is likely to have been thrown off by this product. I'm fairly certain that it's the Taylor test based on 2 things. Firstly, the amount of salt I added should not have been enough to raise the level above 4,000 based on the charts from the Aquapure manual.
But more ****ing is that if I take a water sample, add 1 drop of this product to that sample and then do the Taylor test, I gave up trying for the colour change after around 40 drops of the R-0718.
I've sent a note to them asking if this product could cause the erroneous test results, which if so, I would have expected a warning as they are (supposed) salt pool experts.