Hello; I have not used flourite so cannot comment from experience.
Here is a link to about flourite.
http://en.wikipedia.org/wiki/Fluorite
Have i found the stuff you are using?
I have used commercial solid plant tabs that work .
I tried an experiment a while back with potting soil. I put some potting soil in a jar and added enough water to make it damp (had to let it sit around for a bit). I then packed the damp potting soil into empty plastic 35 mm film containers. I put the containers in a freezer untill frozen. Getting the frozen soil plug out of the container is perhaps the more challenging part. I have been able to get the frozen plug of soil into the gravel near my amazons roots usually without too much getting freee into the water (some does float free). I saw a growth response in the swords soon after adding the plugs.
I have been trying to think of some better way to make the frozen plugs easier ot extract and also to insert into the substrate, but have not tried anything new as yet.
