I have a RWDC and it holds 400 ltrs total with a 60 ltr top up res that feeds the system, I have 9 plants that didnt alter the EC until about 13 days about 12 inchs high and then they were using 50pmm a day at about 21 days 24inch I noticed just a slight hooking off some of the bigger leaves, I run two strains White Rhino and Bubba Kush and both were showing the same symptoms , so what I did was bleed off 60ltrs a day and let the top up fill up the system, next day bleed of another this is now the 5th day of bleeding off and replacing 60 ltrs a day and the leaves have straightened out, I believe the hooking was the beginning of a deficiency or a toxicity from the nutrient profile running out of balance after 3 weeks of the plants taking some parts of the nutrient and not others so the balance runs out , Ive read guys saying they ran the whole grow without a change I wouldnt attempt to run without changing the res, not from what I could see was going on with my own plants.