That much opf a temprature swing could hurt a lot. 2-3degree's F is enough to cause chaos in some tanks. heaters are one of the the cheapest part of your tank, and also one of the easiest ways to lose everything(I've had it happen
)and throw a $10 walmart mini fan on the top that turns on when your lights turn on.
You've been given great advice about the baserock, a clean start would be great. With the cost down now it's a cheap way to start aswell.