I'd keep two of the astrea snails (assuming you dont have large mexican turbo's), get five small nassarius and about three cerith. I'd lose the urchin and emeralds. I'd probably lose a few of the hermits too. I'm not a big fan of excessive clean up crews. at some point wether you know it or not if your sustaining a large clean up crew you are feeding them or masking the route of other problems. I had in my my 30gallon reef had 5 hermits, 2 snails and a cleaner shrimp and the tank was no more worse for wear then when it had 10 atrea snails, 25 hermits, 2 emeralds and a sally lightfoot. After natural selection the numbers dwindled down to a modest amount anyway and remained consist there.