something else to keep in mind is when you gravel vac you'll stir everything up and make a mess.
Hmmm...I'd really like to have a white sand as a substrate but if it mixes maybe thats not a good idea to mix. But at the same time I dont want the fluorite to go to waste and I would like to give it a try.
What if I physically separated the substrate, like little pockets of the fluorite where the plants will be but sort of hidden by the hardscape. Any ideas how I could pull that off?