Yeah its supposed to work with tap water, and apparently works perfectly for some but obviously not for me. No need to PH was the biggest selling point for me since PH pens are expensive and need regular maintenance. Not to mention if my hygrometers all give different readings I can imagine a PH pen could tell me 6.2 when it’s actually 5.2 or 7.2 just seems nothing fucking works how it’s supposed to anymore. It’s all mass produced garbage with no quality control. That’s another reason Mantis, created by a guy with credentials in plant science including a PHD in plant virology sounded good. Not to mention, it seems everyone still has problems with the “tried an true” methods. So it seems like a craps shoot either way.