How to keep water res temps ?

As winter is upon us ( mid August) lol temps are getting cooler and humidity is rising .

My tent is currently empty and is sitting at 19°c 90% humidity .

Going to start dwc I. A couple of months and it's going to be chilly. Probably about 13-15°c

Lights on is never an issue . And might have to get some sort of cheap heater

Ive never grown dwc and have no experience with water temps .

How tricky is keeping water temps stable especially during winter can I get some sort of aquarium heater that is cheap to run during lights off .

Or would I be better off just hearing the entire tent and the water will follow

Probably easier to heat the room a bit overnight. I generally don’t and my room gets down to 14c in winter overnight. I usually run my reservoirs on top of heating pads connected to speed master fan controls (basically rheostats) so I can adjust the heat. I use a timer and turn them on at night. You could use aquarium heaters. The only reason I don’t is it’s another source of power into the water and there’s already a circ pump in there. Just didn’t like the idea of working around a tank with another power cord going into it. A heater in the tent would be fine too. Bigger res is more stable for ph and temps so that will help if you have one. I run the waterfarms some and they work ok sitting on a heat pad but only a 2 gallon res.