Originally Posted by djmarchand
DHays makes an interesting observation, one which led to a heated exchange some years ago between me and the venerable Tony Athens. If you fresh water flush then maybe you need aluminum engine zincs because 95% of the time they sit in fresh water. Aluminum works better than zinc in fresh water.
I read through that entire thread on Boat Diesel between you and Tony. Notice, I elected to start using AL anodes rather than zinc when I started doing the fresh water flush.
One of the concerns is that many knowledgeable folks report that zinc anodes develop a surface coating that becomes less reactive when used in situations where they are intermittently exposed to fresh water. Some boaters think this is a good thing as they don’t have to replace them since they then last a very long time. However, I don’t want my anodes to last a long time. They are supposed to be sacrificial anodes after all.