I just learned another interesting thing about RKs:

I had to sent back a PC4 because it was messing up the controller. They said the symptoms were consistent with water damage but there where no signs of water damage whatsoever and they replaced it under warranty (the thing never got wet or anything. There was no power outage, etc.)

So I asked if I should plug the PC4s into surge protectors. (my husband hates that extension cord thing though) and mentioned that now I have them plugged straight into the GFCI outlets.
They said they do not recommend GFCI outlets for the PC4s since it can cause damage (not sure how -maybe Alton can explain) to the PC4.

So anyway if you have a choice (I don't I converted all outlets and circuits by the aquarium to GFCI - I do have multiple circuits though so if something trips not all of it goes out), don't plug the PC4s into GFCI outlets