I'm using tap water butnits good quality water . Yes they are drinking a lot , did the nute change Saturday I think by sunday night , I added 10 liters of water , that might have been a bit much.What kind of water and nutrients are you using? I had a similar thing going on when using future harvest. Are the plants drinking lots of water that would explain the TDS climbing so much, as well as the PH dropping because the nutrients are acidic so as the concentration gets higher the PH will drop.
I am not using future harvest nutrients, I am using locally sourced "quick grow" nutrients.
Thanks for the quick reply.