I also use GH nutes and DWC buckets. For me, this looks like you haven't done a full res change since you started. You need to change the res completely at least every 2 weeks (although 10 days is probably better).
Other possibilities include not using any calmag. This is 100% necessary if using RO/distilled water. You can't get around it. CALiMAGic from GH works very well!
I also use Diamond Nectar for the entire grow and strongly recommend Floralicious Plus for flower.
DM me if you have issues, as I have experienced and solved a whole slew of problems with your setup.