What are your res temps? Algae, dead roots, etc can make the pH swing - how do your roots look? Have you lightproofed your buckets?
I almost lost my first DWC crop due to my res temps getting out of control and root rot setting in. The plants looked very wilted looking and there was...
It seems your water is a little on the hard side and that can play a factor in trying to get things stable. If you don't have a RO filter available, try picking up some Distilled water and I bet you see things levelling off.
What size res? What nutes or additives do you have in the res? Are you using RO or tap water? I noticed pH swings with FF nutes in my DWC, but when I switched to the DM line my pH became stable as a rock.
pH is a great indicator of what's going on in the res as well. it will change a...