I imagine the first step would be to use standard marine anti-foul paint on the exchangers. But that only works for a few months at best. After that, I'm not s

I imagine the first step would be to use standard marine anti-foul paint on the exchangers. But that only works for a few months at best. After that, I'm not so sure. Perhaps a slow, continuous movement of an exchange surface past a hard surface would do the trick. When this stuff is young, it's easily wiped away, but once it's there for a while you get real problems.