Thinking of adding serpent star

I am thinking of adding a marble serpent star (from what I've read this one is considered a brittle star) to my 29 gal biocube. It's about 4 months old (the tank) and houses 2 mandarins, 2 clowns, a bubble tip nem, a feather star, and 2 emerald crabs. Don't worry, one of the mandarins is already eating mysis and blood worms, am continuing to add a bottle of live copepods every other day until I either get a farm going or ween him onto prepaired foods. But is there any reason I should not get a marble serpent star with any of these tank mates? I've read that they are great cleaners, eat waste, and are very peaceful (also only get about 10 inches tip to tip). Any info You can offer is much appreciated. Also am I putting in enough copepods for the time being?

 

Too small of a tank I'm afraid.

It'll deplete your sandbed of all life, then die. This will also be counterproductive to sustaining two mandarins.

Good luck.