Root ph

I would try and keep your PH at a stable 5.8 and only go up to 6.2 when you start to enter flower. If you notice that PH is drifting your plants maybe they are feeding more then expected. Have you been monitoring your EC of the feeding solution? Is it dropping a lot over 24hrs and does coincide with the rise in PH? You could try and do a flush to get the PH back to normal and then go from there, but before doing this I would recommend making sure the above values PH/EC are checked first. If you do not have a TDS pen I would suggest you get one. Good Luck!