I am in low brackish water on the creek, and I have been letting the 2 heat exchange anodes go to pieces and not replacing them. I have Sendure and the tubes and parts are nickel-copper from what I read. When I first got boat, some dummy let the water freeze and cracked a few tubes. I had to silver braze several shut on both exchangers, and that was in 1998. Been working fine. I do in the winter drain them so they sit dry for a few months If it was full salt water I would be more concerned, BUT they are originally made in 1970. AND the cruisair heatexchanger nickel copper tubing is a unit from 1971, and has never had anodes and it is in great condition, so maybe its overrated, IF your heat exchangers are more than just copper and the water is not very salty.