I went with these:
http://www.specialtyalarms.com/site/...product/80-519
I picked these based on that they can be either "normally open" *or* "normally closed". Some seem to be either one or the other.
I figured if I use some that are normally closed, then I can run a number of them in series - have a few spots on the floor that are the usual spots water might accumulate if spilled, but only use up one monitoring circuit on the Apex. Just a sort of "there's water on the floor somewhere in the tank room" general alarm is good enough, I don't need granularity to the point of "spillage on the left" or "spillage on the right" 'cuz it's more that I want to be notified if I need to hurry home for some reason rather than "you're a klutz and spilled water during a water change" because I might kinda already know that already without my Apex needing to tell me.
