I live in Alaska and as you could imagine it is starting to get cold. This is my first attempt at DWC hydro everything seems to be running smooth but my nutrient temperature is dipping down to 57-58 degrees. Is that getting too cold? How cold is too cold? Will this slow things down? What is the perfect temperature range? And how hot is too hot 73 degrees? I'm thinking of getting a aquarium heater, or a reptile heating mat what would be best? THANKS!