I did some more research and I've narrowed it down to a tiger sea cucumber and/or a sand sifting star. Both would be good at controlling
detritus alage and star would be good overall janitor for the tank.
Saltwater Aquarium Inverts for Marine Reef Aquariums: Sea Cucumber, Tiger Tail
I also found out that not all sea cucumbers will omitt toxins when die. I guess mostly the filter feeder types do this. Can anyone confirm or deny this?
Saltwater Aquarium Starfish for Marine Reef Aquariums: Sand Sifting Sea Star
The engineer gobies do not eat
detritus alage and nassarius snails do more scavanging that sand sifting.
