wrote:

I've bought
flourite for a substrate, live in central FL, the house temperature
hovers around 78-81 in the summer but in the winter we open the
windows a lot so the temperature might be more in the low-mid
seventies. Will the cables be effective at these temperatures?

The most enthusiastic fans of heating cables seem to live in cold
climates or high altitudes. The vast majority of us don't use them. In
your climate, you certainly don't need them.