i found a good deal on a mr. beer kit and purchased it. the instructions seem the be fairly easy and for my first time i plan to follow then to the letter. the only problem i anticipate is temperature control. mr. beer says 68 to 75f. just how close and constant must this be? can someone give tips on how to maintain the target temps? i have more than the layman's knowledge of chemistry and biology. when i grew mushrooms i used an aquarium heater in water to maintain the temp and humidity when fruiting. i need tips on how to do it for brewing. tia!