Mooring anode

[gljnr1983]

Id like to try an anode on there mooring chain i am thinking about getting a 35mm shaft anode and attaching it to the second top link on my ground chain before i lay it.
I am thinking the rubbing on the ground will keep it clean and working to but not sure if zinc is the right anode in fresh water,anyone tried it?

 

[alahol2]

Magnesium is the usual anode quoted for fresh water, or sometimes aluminium IIRC.