Hi, Everyone, I am im need of replacing my anodes for my 94 alpha gen 2. I am going to be using this in strictly fresh water. I know from reading around Magnesium seems to be the best for fresh but can I use aluminum instead and be alright? The magnesium anodes as $100 vs $50 for aluminum. If I had the money I would go for the magnesium but at this point I think having some kind of anode is better then none.

If you are going to leave the boat in the water use magnesium, cheaper than a case or transom assay. If you are trailering and just go out for the day and pull boat out, use anything.

I'm not too sharp on cathodic protection, but I do not see how an aluminum anode will you help you since some of the parts you are trying to protect are themselves aluminum. Your electrolyte it less potent, being freshwater, but I can't say that choosing the $50 anode over the $100 part will net you any savings.

If you'd like, I'll ask our corrosion team on Thursday when I see them next.

EDIT- My comments were for a passive cathodic system, if impressed current is used I'll have to reevaluate. Either way, I'm gonna ask our corrosion gurus.

Here is a little info.
Anode FAQs

Thanks for the link. So according to that one chart I can use aluminum for fresh water. Like I said I would use magnesium if I could afford it. Fresh water is not so corrosive, if it was salt water that is a different story and would have to go for the best anode.

If it was salt water you definitely don't want magnesium. Fresh water is not as critical. If you are going to leave the boat in a marina the anode to use would be magnesium

have you tried ordering form here?

Mercruiser Sterndrive Magnesium Anodes

I just got my Magnesium FAST and CHEAP!

I just ordered the magnesium ones from there. I got it in the mail the next day. Thanks for the link!