Aluminum and anodes in freshwater

[SWHNA]

Every reference I've found makes recommendations for size and location of zincs on an aluminum hull in salt water. I realize that fresh water is a poor electrolyte, but it seems that assuming some potential for corrosion is preferable to assuming none. Does anyone out there have information or a recommendation for sizing of zincs on a 50' aluminum hull in freshwater?

[marshmat]

I'm no authority on this of course, but if it were me I'd go with similar anode specs to the saltwater version. If you can find magnesium anodes, they will be somewhat more effective on aluminum, but will probably not live as long.