If this topic has been previously discussed, please point me to the proper thread. Thanks. Please note the discrepancy between the post below and the West Marine advice in the next following paragraph. Any guess on who is right. Or are they both saying the same thing for a boat in very clean fresh water. What about magnesium bubbling the paint on the boat? dj Recently on the Catalina 34 Discussion Group someone posted the following: "Also, the zinc anodes are worthless in fresh water. They "go to sleep". Aluminum is the answer, it's lighter, more active and lasts longer. It can also be used in salt water. NEVER use magnesium as it is so active it will cause the paint to bubble & peal off the boat. It also should not be used unless the water is free from polutants. The PH needs to be about 7 for them to work properly. I have seen so many zincs during my surveys and never realized they were worthless on the lake." West Marine States: "Which anode is right for you? Zinc or aluminum for salt water: If you are a saltwater boater, you should install zinc anodes to prevent galvanic corrosion on the engine and underwater parts of your boat. Look for aluminum anodes as a possible replacement because they last longer while providing the same level of protection as zinc. Magnesium for fresh water: Since freshwater is much less conductive than saltwater, magnesium anodes are the best choice because they’re more active (less noble) than zinc or aluminum so they will protect your engine parts much more effectively. Caution: do not use magnesium anodes in any application other than a freshwater because they corrode rapidly, exposing your boat and engine to possible damage. Aluminum for salt & brackish water: More active than zinc, aluminum anodes are a good compromise for a mix of fresh and saltwater, e.g. in the brackish water of river deltas. In brackish water zinc is too passive and magnesium corrodes too rapidly (because of the water’s salt content), leaving your boat without adequate protection."
