The plants and their roots look great! Your plants, for their size are "drinking" right around what I would expect... The thing I would say is go on to flower. Lolly pop trim, 24hrs of dark, move timer to 12/12 and begin flower formulation of your nutrient formula of choice. I've run blue cheese and it seemed to be a thirsty plant for my pheno, all though she didn't "empty" a 5 gal pail until flower (didn't have it so big in veg either). When running DWC. I do a 30% add-back formula. That works like this. In bolth veg and flower. When the "tank" drops to the point that I need to "add-back" or "top-off" (generally every day). I'll mix up "add-back" solution at a rate of 30% of the REGULAR strength of the starting formula. I.E. , if you use 20ml of "grow" and 10ml of "zyme" with 5ml cal/mag,,,,,Then you would use 6ml of "grow" - 3ml of "zyme" and 1.5ml of cal/mag to make the "add-back" solution and top-off the tank. You do this until you have reached the SAME AMOUNT THAT YOU PUT IN TO START!!! Then you dump the tank the next day and refill with 100% strength nutes and repeat the process. That helps with nute costs and keeps the plant in the peak of health. DWC is a FAST growing method, so I'm not surprised at your size vs. time in tank....
In DWC, , I like to be very fussy about pH and keep it between 5.8 and 6.2, with 6.0 being my target.
Ah yes, it's fall and it's time to get out my DWC equipment and sanitize and get started....Maybe some L.A. Confidential or some "Iraqi Hash Plant" (seeds brought home by friends from the Iraq "war")....
Good Luck