Our specialized Navalloy aluminum anodes may be used in all types of water- fresh, brackish or salt. They are long lasting and a great alternative to magnesium or zinc. If your boat is kept on a boat lift or on a trailer, you should not use zinc - as it loses it's effectiveness after removal from water. Navalloy works well in all water types, is long lasting and offers very effective protection. Navalloy is very effective in fresh water also, and much less expensive than magnesium.