For herbivores in my 75, I have one yellow tang and about 10 hermits, 2 emerald crabs (they are great IMHO) 15 turbos, 7 narsius, 3 lettuce nudi's, 2 fighting conchs. I use either distilled or RO/DI water only and dose with Kalk as needed.
The cleanup crew takes care of the alea in the main...