I went looking for something similar, and decided in the end I’d use a temperature sensor on an ESP8266, and those test strips for everything else.
Ali is weak on details, so like you said you’d need some outside source for info and reviews. All the chemical sensors (PH, Chlorine/Bromine, etc.) I found had components which needed to be replaced on a regular basis. Without a guaranteed source for those, from a reliable manufacturer, the whole device could become obsolete. And if I’m using disposable parts anyway, the test strips are just as easy and a lot cheaper.
Still, if that device on Ali does what it claims, that’s not really a bad price, as those things go. Unfortunately my spa is usually covered, so solar power is not an option for me.
Thanks for the info. I’m not familiar with that device. How is it used? Is there a tutorial for this particular use case? I mean, the pool temperature measurement.