Like NM I have a 55 gallon filtration tank which to me is its own living breathing ecosystem that just happens to be attached to the main tank.
I have a good 4.5-5 inch sand bed made from ootlic style aragonite sand.
Chaetomorpha algae and Several hunks of live rock.
I have witnessed the pod larva floating in the water column, I have a growing number of amphipods, copepods, isopids and have several chitons running around.
I have Fire worms, Terebellidae, Cirratulids and Sabella worms, melanostigma, chaetopterid worms, and spirobidae worms all over the glass rocks and even the heater.
I also have a couple of unknown hermit crabs, a red leg hermit.
A fighting conch, micro snails, Turbo snails, Stometella vara , a nassarious snail and astrina starfish.
There are even sponges growing in there.
I did put a mini brittle star in once but never saw it again, shame to because it had 6 arms.
I do feed it some frozen mysis or plankton about once per week, I also feed the tank DT's phyto plankton and cyclopeeze at night.
Fuge is lit at night with 80 watts of NO lights. 2-48 inch Aqua D bulbs by URI
Thomas