The only critters that you really don't want are mantis shrimp, very large bristleworms, and there are some worms that are bad if you are keeping clams. Also large hermit crabs and predatory crabs can be a problem sometimes. There are also some parasitic amphipods although rare.
I do however plan on having a mantis tank sometime soon. If I can find a pretty spearer type I might go with one of those, otherwise I think I might get a peacock smasher.
3' fine sand bed 1x Orange Stripe Prawn shrimp goby, 1x sixline wrassemated pair of true percula clowns, 1x CBS shrimp, 2x peppermint shrimp, 1x pistol shrimp, 1x tiger tale cuke
, ~20+ snails, ~10+ hermits, 1xserpent star.
green Bubble coral, hammer coral (8 heads!) ,various Zoos,green finger leather, green star polpys ,shrooms
175w 10k MH
28w actinic 03
2x maxi jett 1200
Prizm skimmer (modded)
Hagen powerfilter(for running carbon 24/7)
nano arctica chiller