I've got a Hanna combo meter, and I can't seem to pH RO, or the light feeding some recommend. I can get the pH down to 5.9, but within five to ten minutes it'll be back up at 6.3, without fail. I could probably dump an entire bottle of pH down and still be above 6 within a few minutes, what the fuck is going on? I assume the rest of you don't spend hours and hours pHing your flush, right? I'm starting to suspect that this isn't a real thing, just a lie used to get people to give up on growing. :/ EDIT: The meter is fine when it comes to normal solutions, this behavior has persisted through two meters, and multiple probe replacements. EDIT: 5.7-6.3 in about 15 minutes again. What the fuck.