We're about to repaint the bottom of our 50' boat with an ablative
paint that, as far as we can tell, doesn't contain any biocide other
than the copper content (which is pretty low, about 25%). We'd buy a
better paint, but that's all we can get where our boat is, in Turkey.

Are there biocides that can be added to bottom paint to keep the slime
off? The ones used in commercial paints don't seem to be available by
themselves. We've heard of people using tetracycline and even chili
peppers, but don't know if there's any real data to support those, and
besides, don't have a clue how much to use. Any ideas?