What is the average spacing on the horizontal and vertical plane, how many weeks of how many hours of 600 watts lighting from cutting to finish and at what room and reservoir temperatures? As you give no PAR readings or lumen readings I assume you used no meters to determine your diameter but are basing the diameter and number of tiers merely on past experimentation of yours or someone else who also took no readings? No DO readings either? A DO reading of the inlet and outlet nutrient water with preferably a few in between would be very helpful also.
No offense but such data is more useful to me than pictures or final yield results not related to total kWh used for light.
Based upon what information was given it looks like a good methodology for a low temp, therefore slow grow. You have also stated that the DO is dependent upon the fast flow of water through the tubes and relating that to a waterfall aerating water due to your drop from tier to tier or the turbulence created by any fall over the adjustable walls. What is the pitch to your tubes from one adjustable wall to the next, as other than adjusting the walls the pitch will determine the fall and therforethe amount of turbulence. Have you thought of introducing more air into the system such as with an air pump rather than depending just on the air coming in through your pots growing medium to supply O2 at the air-water interface surface, or maybe using a venturi in the water line.
Measured emperical data can not be checked against future trial emperical data (be repeated) if it is not known. Although observations are also considered emperical data, experimentation of real use should contain as much measurable emperical data as is possible. Pictures are just pictures, they are merely guides or records of visual observations. Pictures of PAR readings, CO2 ppm readings, temp and DO readings would be of more use.
