Trigger in sps dominated tank

[Dez]

Anybody have a trigger in an sps dominated tank? I'm thinking about adding a Niger, or Crosshatch, or pinktail trigger. I'm just worried about my clams and crabs, and also water quality. However, my display is 150 gallons but I do have over 300 gallons in water volume.....

Also, I'd like a pygmy angel of some sort, but how to "test" them before putting them in the display to see if they're nippers?

Suggestions appreciated. Thanks.

Des