Keeping mutt guppies outside: Winter in Wilmington, North Carolina

[Sandra the fish rookie]

Hello, 

I have LOTS of guppies, I LOVE guppies. I have them in one of my tanks, and I have a mini pond that is in my 3-season room. It is a converted screen porch that has 10-mil polyvinyl sliding panels that keep it warmer in winter. I keep them all closed, and the pond has an ACO heater set at 80. but this week it dropped to 49 and the tank was at 67.9. but warmed up throughout the day to the mid-70s (ranges between 76 and 78ish). I check it EVERY single morning to see if they are okay. They are pretty lively and happy so far. 

I have had rice fish, but I wanted to try guppies. but I am worried. should I add another heater? Should I move the heater that is in there to a different place in the pond? It's just under the waterfall. My plants have been in there for way over 2 years. and they live all the way through the winter without an issue. The pothos have been there since the beginning. The pond has been set up for over 2.5 years. The deck is wood and screened for bugs. but I plan to put vinyl plank flooring in the spring.

The pond is around 10 gallons. There is a central pump filter, then a sponge filter, substrate, and plants inside as well (Java fern, Val, and Anubis). 

I am a bit nervous... should I take them out? Any other recommendations are happily welcomed. 

[JettsPapa]

Guppies do okay for me when the air temperature gets down into the mid 50's, in 20 gallon unheated tubs, but I don't know what the water temperature goes to.  I don't know if that helps or not.

I don't think anyone can give you a definitive answer on whether or not you should add another heater without knowing how low the air temperature will get, or for how long.  Is there any chance you could move them to a larger container?  The water will change temperature more slowly with larger volume.

[Sandra the fish rookie]

Thanks for your comment @JettsPapa, I don't have anything larger outside. I am keeping it full right to the top, which helps. If I see its too unstable, I will move them into a tank inside. I don't have any over stocked tanks. so that should not be an issue. 

Thanks again for your response. its appreciated. 

[Shawnmrose1983911]

I to have kept my guppies outside in my pond till the air got down to the mid 50s water temp about 61 and had no issues was a long process of getting them warmed back up to go inside for the winter but if your worried I would just set a heater to its lowest setting and you should be fine