When/if to add a sand sifting starfish

First let's please try to avoid a discussion about the pros/cons of a deep sand bed.

I was wondering when and if there is ever a good time to add a sand sifting star (SSS)?

Below are my tanks specs (I'm sorry this is so long), and it has been up for four months

Physical:
55 Gallon with 20 Gallon sump (no skimmer or filter socks)
Small (maybe 2 gallon) refugium -currently building two ten gallon refugiums to add-on-
7-8" Deep Sand Bed

Dosing:
Only Iodine

Feeding:
Morning= Live pytho and dead (seaChem) Zoo plankton
Evening=two cubes of Emerald Entree and one food of some frozen carnivore food
Night=Algae clip (right at lights out)
All Day=Caulerpa (Ulva and Red Gracilaria coming soon)

Stocking:
-inverts
--Hawaiian feather duster x2
--flame scallop
--Sea Hare
--Long tentacle Anenome (can you see why I call my username what it is yet?)
--long spine urchin
--Snapping shrimp
--Scarlet Hermits x3
--Blue legged Hermits x3
--Asteria Snails x4
--turbo snail
-- "Sand Conch"

-fish
--Banggai Cardinal x3 (for now)
--firefish
--Maroon Clown (peaceful little guy)
--yellow watchman
--Yellowhead jawfish (pair)
--engineer gobies (pair) (contemplating removing them too)
--gold banded goby x2 (was brackish tank pre-saltwater)
--guppy (same brackish excuse)

-corals
--zoas
--toadstool
--mushrooms