Some floatplane operators on Back Bay have been noticing corrosion and/or discoloring of their floats over the last few years. Sacrificial anodes mounted on float keels could provide some protection for floats.
Marine anodes are commonly used on aluminum boat hulls, and should also work on aluminum airplane floats, in the hope of preventing or resisting corrosion and/or discoloring of floats due to chemicals in the water. The anodes come as a set of two 2” diameter disks connected by a bolt. They can be attached on either side of the keel, either by placing the bolt through existing small holes, or by drilling holes to mount the anodes. The anodes work because contact between dissimilar metals produces a dielectric current prompting corrosion of the sacrificial anode in protection of the aluminum. See the following article for further explanation: "Choosing the Right Sacrificial Anode".
As part of its liquidation sale, Force One is selling lead marine anodes, regularly priced at $8 per set, at a 30% discount. They can be found in a large round candy jar beside the cash register/computer on the parts side of the store. Two sets would be needed to protect a set of floats.