Are Vermiculite or Perlite really necessary? Can't I just insulate the base with sand instead?

Vermiculite and Perlite are known as Nature’s Insulation. And sand… well, sand is just boring 'ol sand. Nothing sexy about sand.

Vermiculite and Perlite retain heat exceptionally well and hold that heat for extended periods of time. Sand on the other hand doesn’t hold heat very well, so it’s not a great insulator.