bz, sounds like you have really acidic natural conditions, are you in a conifer belt?
if you have a local source of quarried limestone, call and ask for the 1/2-inch to minus (or just the minus if they screen it that fine). put around shallows and edges, cant hurt, could provide a good spawning substrate and possible localized pH affect - ewest raises great point that you might get a whole micro-ecosystem on it, provide diversity in small critter forage.
