No, I believe it is inert. It has high cationic exchange capacity, that's it.
Just a quick clarification; Flourite (#19) (CEC = 1.7) does not have a high CEC like the Montmorillonite clay materials such as Turface (#16) (CEC = 29.8-41.1) or Safe-T-Sorb #7941. Although Flourite has a relatively low CEC it does contain a lot of mineral nutrients essential for healthy plant growth; although the low CEC would bring into question the ability of Flourite to release those minerals to plant roots.
CEC Values of Various Substrates and Additives (per Planted Aquaria Magazine issue #2)
Last edited by Seattle_Aquarist; 11-21-2013 at 02:59 PM.