I dont panic over pH as much as most ppl....a drift is the best...IDEALLY, I like to start at 5.7 cause I usually get a little up drift...It seems 6.0 is a sweet spot for mine...So I set a little lower and let it drift up to a little over 6.0, and reset again next watering....ANYONE trying to pin down a pH # to ZERO drift, will drive themselves crazy, and its not necessary...If your btwn 5.5 and 6.3 with a Hempy Bucket, your plants will be fine...understand the drift and use it as an advantage...Better nute absorbtion that way.....Of course, if your heavy feeding, you get a DROP in pH and light feeders see more of a pH rise....Kind of a nice additional gauge for proper ppm levels...tends to stay put when tuned...problem is the plants grow fast and your never tuned that close for that long, so a little drift just needs to be embraced instead of chasing it all over....FLUSHING,,,I run thru flower without CHOKING my plants too bad with nutes....2 weeks out from harvest I cut nutes in half...they start yellowing in a few days..and no nutes last week (10 days if the need more ripening)....
REMEMBER, my medium is CLEAN from nutes..I am watering down my 2 inch pvc tubes...When I cut down on nutes (and then stop them), those internal reservoirs rinse out immediately with runoff....I HATE FLUSHING, and watering that way eliminates it....buds smoke clean as they should!!!!....IF I DIDNT, have the PVC watering tubes, I would use the same nute reduction schedule, while top watering.....You pretty much know by the looks of your plants a cpl weeks from harvest, if you been heavy feeding.....problem is just flushing the medium wont cut it, IF THE PLANTS cant process what they stored up....if your flushing 2 weeks prior to harvest, AND STILL have Green plants at harvest time, your feeding too heavy thru flower...One way or another, they GOT TO CLEAN OUT....Nothing worse than smoking a bud still loaded with chemicals....SNAP, CRACKLE, POP, CHOKE, PUKE...LOL