I've been running with my build for about a week now, and the plants are coming along nicely! But today I noticed something that I consider to be pretty serious. I was going to relocate the placement of some seedlings to other holes, and even to the touch, I could feel current running through my fingers from the horticubes. I removed the foam board and plants, and it was evident that there is some sort of buildup of static or electrical problem with my pump. I've turned off my FC, but I still get zapped by touching the grow water. I worry for the plants and the electronics since this is not some slippers-on-carpet one-off zap, but a continuous tingle.
So, since I think we can make the intellectual leap that my plants probably don't have superpowers, I'm guessing that running the pump and air stone 24/7 insulated by plastic and foam causes legitimate static buildup if not grounded correctly. Does this seem correct? If so, I'm considering a simple solution by running a copper wire hooked up to wall ground (GROUND, not the live wire) into the water, but if the buildup is occurring on the plastic or foam I can't be sure as to how effective that may be.
I grabbed my voltmeter and stuck one probe in the water near the pump, and the other on the DC power supply ground (probably not encouraged in the user manual) and got readings peaking near 0.2-0.22V, which doesn't seem like an insignificant amount of potential.