Fluorite is one of the best substrates you can buy, if you want strong healthy plants.
Washing fluorite is a little tricky, but not all that hard as previous people have described. First of all, PLEASE DO NOT rinse it the way the previous reviewer described! You'll make it even worse, and make the fluorite break up into tiny pieces. That's the WRONG way to do it.
What you want to do is get a pan with a lot of surface area and not very deep. Fill the surface with the fluorite, put the hose on low flow and lit it run through the fluorite. Swish it slightly, but don't dig your hands through the fluorite. The loose particles will float into the water, and out of the pan.
You won't be able to get all of it, so just get as much as you can. Once rinsed, separate it and allow it to dry slightly. Then repeat until all of it is cleaned.
When putting it in the aquarium, fill it first, then put in the fluorite. You want to avoid putting water directly on it, and sifting your hand through it as much as possible, to keep the particles as large as possible.
Once cleaned and settled, vacuuming is okay. You don't want the fluorite filled with too much waste, because it can prevent plants from growing, and even them rot away.