Cleaned up my prototype a bit by moving it off the breadboard and soldered to a smaller perf board. Also added some screw down terminals to connect the external sensors.

One problem is that now the PH sensor is always reading a PH of about 2.5. Either I have something wrong in the wiring (I dont think so), or the probe went bad. I heard that these probes can be a bit weird. I am going to try to attach to a Leonardo Arduino and see if I get different results there. (ie. bypass my ADC converter and just read the analog directly on a real arduino).

The results of the build are below. More to come later.