Thanks for the comments.
I've had these clowns for almost 14 years. (Purchased August 1994) The female has always had the missing section of her dorsal fin, and some uneven melanistic markings. (Birth defect?) The melanism has increased with age and spread to even the white areas of her body.
Regarding the caulerpa, I harvest 75-80% of it every month or so. I notice that my hair algae growth is much less with the macro-algae growing in my tank, so I guess it's a trade-off.
A comment: I have noticed that many pairs of clowns show less sexual dimorphism than mine do. My male still looks like a juvenile with a 'cute' appearance despite his advanced age. I know his parts 'work', though, because I have seen the developing eggs. Here's a pic of him tending the eggs. Picture:
<img src="http://i13.photobucket.com/albums/a269/Scifish/2007%2001/200701ClownfishEggs005.jpg">