Keeping tropicals in pond with heater in Florida?

[Sawyer]

I'm in Florida (on the northeast coast) so during a lot of the year it'd be warm enough for tropicals. I was wondering if it's a good idea to keep tropicals outside in the winter and just use a heater?

What kind of ponds can you use heaters in? Like would it be safe in those preformed ponds or in rubbermaid stock tanks? I'm guessing it wouldn't be safe in anything plastic, like plastic kiddie pools?

 

[Ed123]

In my case (hills just southeast of the LA basin) I just have a 200 gallon tank outside with a heater. What I do when it gets cold is set up a "greenhouse" to put over it and an acrylic top that fits snug ontop. The top keeps evaporation down, and the plastic cover (greenhouse if you want to call it that) keeps a warm humid buffer that can be about 10 degrees warmer, possibly more but it hasn't ben through a winter yet. Either way it keeps heat much better than our old outdoor 55 gallon.
FYI- Our winters get down to 40 degrees

 

[Ed123]

http://m.instructables.com/id/Build-an-Easy-5-x-5-Home-Greenhouse-for-under-25/ I just use something like this