Which filter can filter out floride?

There is no filter that can filter out fluoride. Fluorides are in solution form and in ionic state. These can not be removed with mechanical filters but ion exchange resins can remove the fluorides due to their affinity towards these resins. The other reliable process to remove fluorides is reverse osmosis. In reverse osmosis or RO plant as is known the dissolve fluorides are removed from water with help of selective permeability of special membranes