[Gatto Nero]

This is my first year using an aqua-therm around my dock and I have a couple of questions that I'm sure lots forum members have opinions on.

I have a 1/2 HP de-icer strung between two docks that form a U. It hangs about 4' down in about 6' of water. I also purchased a time and temperature controller. I currently have the temp gauge set to 30 degrees.

My questions are:

1) Is that temp setting OK or should it be higher/lower?
2) How long and how often I should I have it run when it drops below the set temperature?
3) Where can I buy the official Danger, Thin Ice sign?

Thanks in advance.