No controller? Well no recirculating for you then!! Just carry on the way you are going.

The reason for recirculating the nute solution throughout the system is to keep all the waterfarms numbers more even and balanced without the ph and ppm jumps you get in each individual w/f. GH talks about how you can adjust ph etc just from your controller but as you have found there can be large changes between each w/f so keeping tabs on the numbers from the controller alone isn't really practical unless the system recirculates. Also water that is moving around also picks up more oxygen which translates to happier plants as well.