Hi I was wondering if anyone else has this issue. I put in my nutrients and fully let it dissolve, then I adjust the pH with pH down and shake it very well and get it to around 6.3-6.4. I fill up a large sprayer and it usually sits in there for about 2 spraying sessions for which by the time I need to spray again, the pH has gone up to around 7. Has anyone else had this issue? I'm using regular miracle grow and nothing that needs to break down over time.