pHin Water Monitor for Pools and Hot Tub

Purchased in June 2018 when I first heard about it. I've used it with a cheap pool from a warehouse store for 2 summers and this year in our new 7500 gallon above ground pool. It's almost always had odd readings, but generally seemed to be in the right ballpark, so I wrote it off mentally as issues with monitoring changes too closely (hourly/daily) rather than on a weekly or bi-weekly basis like most pool care companies would do. Over the last couple of months though the differences have gotten more and more extreme, the first being insanely high (225ppm+) Total Alkalinity readings, but constantly telling me my pH (one of the readings it does constantly) was always below 7.0. No matter how much pH increaser I'd add (often more than their app suggested) my pH has never been above 7.1 for more than a couple of hours. Recently I've started wondering if there was a different issue and decided to start testing myself with highly rated test strips as well as taking water samples to my local pool supply store to be tested. Sure enough the test strips and pool supply store show my pH is 8.6+ but the PHIN app still tells me I'm in the unsafe zone below 7.0. Additionally the PHIN app continually tells me to add sanitizer (granulated chlorine) or chlorine tablets daily, and today is telling me I'm in the "unsafe" low zone and need to add but the test strips and pool supply store test show my CYA levels at 205ppm and free Chlorine at 15, both of which are 50-200% higher than "normal" and nowhere in the same universe as being low like PHIN is reporting. So aside from probably hundreds of dollars in wasted pool chemicals and potentially endangering my daughter with unsafe water conditions due to the inaccuracies of this device, it also requires a $100 a year subscription to provide these completely inaccurate and useless readings. Love the idea of this device and thought it was decent for a while, but it's clearly a problem the fact they can't notify you in the app that there's a potential issue with the sensor (like opposing Total Alkalinity and pH levels) or accurately measure 2 of the 3 elements they advertise as reading constantly. Have never been more disappointed with any pool equipment/accessory. It'd be better if the product just didn't work at all versus reporting completely inaccurate data which could result in serious health issues to anyone using a pool monitored and maintained by one of these.